/* 
   Unix SMB/CIFS implementation.
   Samba utility functions

   Copyright (C) Andrew Tridgell 2009
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2009
   Copyright (C) Matthieu Patou <mat@matws.net> 2011

   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/>.
*/

#include "includes.h"
#include "ldb.h"
#include "ldb_module.h"
#include "librpc/ndr/libndr.h"
#include "dsdb/samdb/ldb_modules/util.h"
#include "dsdb/samdb/samdb.h"
#include "dsdb/common/util.h"
#include "libcli/security/security.h"

/*
  search for attrs on one DN, in the modules below
 */
int dsdb_module_search_dn(struct ldb_module *module,
			  TALLOC_CTX *mem_ctx,
			  struct ldb_result **_res,
			  struct ldb_dn *basedn,
			  const char * const *attrs,
			  uint32_t dsdb_flags,
			  struct ldb_request *parent)
{
	int ret;
	struct ldb_request *req;
	TALLOC_CTX *tmp_ctx;
	struct ldb_result *res;

	tmp_ctx = talloc_new(mem_ctx);

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_search_req(&req, ldb_module_get_ctx(module), tmp_ctx,
				   basedn,
				   LDB_SCOPE_BASE,
				   NULL,
				   attrs,
				   NULL,
				   res,
				   ldb_search_default_callback,
				   parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->search(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (res->count != 1) {
		/* we may be reading a DB that does not have the 'check base on search' option... */
		ret = LDB_ERR_NO_SUCH_OBJECT;
		ldb_asprintf_errstring(ldb_module_get_ctx(module), 
				       "dsdb_module_search_dn: did not find base dn %s (%d results)", 
				       ldb_dn_get_linearized(basedn), res->count);
	} else {
		*_res = talloc_steal(mem_ctx, res);
	}
	talloc_free(tmp_ctx);
	return ret;
}

int dsdb_module_search_tree(struct ldb_module *module,
		       TALLOC_CTX *mem_ctx,
		       struct ldb_result **_res,
		       struct ldb_dn *basedn,
		       enum ldb_scope scope,
		       struct ldb_parse_tree *tree,
		       const char * const *attrs,
		       int dsdb_flags,
		       struct ldb_request *parent)
{
	int ret;
	struct ldb_request *req;
	TALLOC_CTX *tmp_ctx;
	struct ldb_result *res;

	tmp_ctx = talloc_new(mem_ctx);

	/* cross-partitions searches with a basedn break multi-domain support */
	SMB_ASSERT(basedn == NULL || (dsdb_flags & DSDB_SEARCH_SEARCH_ALL_PARTITIONS) == 0);

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_search_req_ex(&req, ldb_module_get_ctx(module), tmp_ctx,
				   basedn,
				   scope,
				   tree,
				   attrs,
				   NULL,
				   res,
				   ldb_search_default_callback,
				   parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->search(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	talloc_free(req);
	if (ret == LDB_SUCCESS) {
		*_res = talloc_steal(mem_ctx, res);
	}
	talloc_free(tmp_ctx);
	return ret;
}

/*
  search for attrs in the modules below
 */
int dsdb_module_search(struct ldb_module *module,
		       TALLOC_CTX *mem_ctx,
		       struct ldb_result **_res,
		       struct ldb_dn *basedn, enum ldb_scope scope,
		       const char * const *attrs,
		       int dsdb_flags,
		       struct ldb_request *parent,
		       const char *format, ...) _PRINTF_ATTRIBUTE(9, 10)
{
	int ret;
	TALLOC_CTX *tmp_ctx;
	va_list ap;
	char *expression;
	struct ldb_parse_tree *tree;

	/* cross-partitions searches with a basedn break multi-domain support */
	SMB_ASSERT(basedn == NULL || (dsdb_flags & DSDB_SEARCH_SEARCH_ALL_PARTITIONS) == 0);

	tmp_ctx = talloc_new(mem_ctx);

	if (format) {
		va_start(ap, format);
		expression = talloc_vasprintf(tmp_ctx, format, ap);
		va_end(ap);

		if (!expression) {
			talloc_free(tmp_ctx);
			return ldb_oom(ldb_module_get_ctx(module));
		}
	} else {
		expression = NULL;
	}

	tree = ldb_parse_tree(tmp_ctx, expression);
	if (tree == NULL) {
		talloc_free(tmp_ctx);
		ldb_set_errstring(ldb_module_get_ctx(module),
				"Unable to parse search expression");
		return LDB_ERR_OPERATIONS_ERROR;
	}

	ret = dsdb_module_search_tree(module,
		       mem_ctx,
		       _res,
		       basedn,
		       scope,
		       tree,
		       attrs,
		       dsdb_flags,
		       parent);

	talloc_free(tmp_ctx);
	return ret;
}

/*
  find a DN given a GUID. This searches across all partitions
 */
int dsdb_module_dn_by_guid(struct ldb_module *module, TALLOC_CTX *mem_ctx,
			   const struct GUID *guid, struct ldb_dn **dn,
			   struct ldb_request *parent)
{
	struct ldb_result *res;
	const char *attrs[] = { NULL };
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	int ret;

	ret = dsdb_module_search(module, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE,
				 attrs,
				 DSDB_FLAG_NEXT_MODULE |
				 DSDB_SEARCH_SHOW_RECYCLED |
				 DSDB_SEARCH_SEARCH_ALL_PARTITIONS |
				 DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT,
				 parent,
				 "objectGUID=%s", GUID_string(tmp_ctx, guid));
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}
	if (res->count == 0) {
		talloc_free(tmp_ctx);
		return LDB_ERR_NO_SUCH_OBJECT;
	}
	if (res->count != 1) {
		ldb_asprintf_errstring(ldb_module_get_ctx(module), "More than one object found matching objectGUID %s\n",
				       GUID_string(tmp_ctx, guid));
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	*dn = talloc_steal(mem_ctx, res->msgs[0]->dn);

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

/*
  find a GUID given a DN.
 */
int dsdb_module_guid_by_dn(struct ldb_module *module, struct ldb_dn *dn, struct GUID *guid,
			   struct ldb_request *parent)
{
	const char *attrs[] = { NULL };
	struct ldb_result *res;
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	int ret;
	NTSTATUS status;

	ret = dsdb_module_search_dn(module, tmp_ctx, &res, dn, attrs,
	                            DSDB_FLAG_NEXT_MODULE |
	                            DSDB_SEARCH_SHOW_RECYCLED |
				    DSDB_SEARCH_SHOW_EXTENDED_DN,
				    parent);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb_module_get_ctx(module), "Failed to find GUID for %s",
				       ldb_dn_get_linearized(dn));
		talloc_free(tmp_ctx);
		return ret;
	}

	status = dsdb_get_extended_dn_guid(res->msgs[0]->dn, guid, "GUID");
	if (!NT_STATUS_IS_OK(status)) {
		talloc_free(tmp_ctx);
		return ldb_operr(ldb_module_get_ctx(module));
	}

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}


/*
  a ldb_extended request operating on modules below the
  current module

  Note that this does not automatically start a transaction. If you
  need a transaction the caller needs to start it as needed.
 */
int dsdb_module_extended(struct ldb_module *module,
			 TALLOC_CTX *mem_ctx,
			 struct ldb_result **_res,
			 const char* oid, void* data,
			 uint32_t dsdb_flags,
			 struct ldb_request *parent)
{
	struct ldb_request *req;
	int ret;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct ldb_result *res;

	if (_res != NULL) {
		(*_res) = NULL;
	}

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_extended_req(&req, ldb,
			tmp_ctx,
			oid,
			data,
			NULL,
			res, ldb_extended_default_callback,
			parent);

	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->extended(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	if (_res != NULL && ret == LDB_SUCCESS) {
		(*_res) = talloc_steal(mem_ctx, res);
	}

	talloc_free(tmp_ctx);
	return ret;
}


/*
  a ldb_modify request operating on modules below the
  current module
 */
int dsdb_module_modify(struct ldb_module *module,
		       const struct ldb_message *message,
		       uint32_t dsdb_flags,
		       struct ldb_request *parent)
{
	struct ldb_request *mod_req;
	int ret;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct ldb_result *res;

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_mod_req(&mod_req, ldb, tmp_ctx,
				message,
				NULL,
				res,
				ldb_modify_default_callback,
				parent);
	LDB_REQ_SET_LOCATION(mod_req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(mod_req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(mod_req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, mod_req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), mod_req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->modify(module, mod_req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(mod_req->handle, LDB_WAIT_ALL);
	}

	talloc_free(tmp_ctx);
	return ret;
}



/*
  a ldb_rename request operating on modules below the
  current module
 */
int dsdb_module_rename(struct ldb_module *module,
		       struct ldb_dn *olddn, struct ldb_dn *newdn,
		       uint32_t dsdb_flags,
		       struct ldb_request *parent)
{
	struct ldb_request *req;
	int ret;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct ldb_result *res;

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_rename_req(&req, ldb, tmp_ctx,
				   olddn,
				   newdn,
				   NULL,
				   res,
				   ldb_modify_default_callback,
				   parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->rename(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	talloc_free(tmp_ctx);
	return ret;
}

/*
  a ldb_add request operating on modules below the
  current module
 */
int dsdb_module_add(struct ldb_module *module,
		    const struct ldb_message *message,
		    uint32_t dsdb_flags,
		    struct ldb_request *parent)
{
	struct ldb_request *req;
	int ret;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct ldb_result *res;

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb_module_get_ctx(module));
	}

	ret = ldb_build_add_req(&req, ldb, tmp_ctx,
				message,
				NULL,
				res,
				ldb_modify_default_callback,
				parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->add(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	talloc_free(tmp_ctx);
	return ret;
}

/*
  a ldb_delete request operating on modules below the
  current module
 */
int dsdb_module_del(struct ldb_module *module,
		    struct ldb_dn *dn,
		    uint32_t dsdb_flags,
		    struct ldb_request *parent)
{
	struct ldb_request *req;
	int ret;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct ldb_result *res;

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_oom(ldb);
	}

	ret = ldb_build_del_req(&req, ldb, tmp_ctx,
				dn,
				NULL,
				res,
				ldb_modify_default_callback,
				parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = dsdb_request_add_controls(req, dsdb_flags);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (dsdb_flags & DSDB_FLAG_TRUSTED) {
		ldb_req_mark_trusted(req);
	}

	/* Run the new request */
	if (dsdb_flags & DSDB_FLAG_NEXT_MODULE) {
		ret = ldb_next_request(module, req);
	} else if (dsdb_flags & DSDB_FLAG_TOP_MODULE) {
		ret = ldb_request(ldb_module_get_ctx(module), req);
	} else {
		const struct ldb_module_ops *ops = ldb_module_get_ops(module);
		SMB_ASSERT(dsdb_flags & DSDB_FLAG_OWN_MODULE);
		ret = ops->del(module, req);
	}
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	talloc_free(tmp_ctx);
	return ret;
}

/*
  check if a single valued link has multiple non-deleted values

  This is needed when we will be using the RELAX control to stop
  ldb_tdb from checking single valued links
 */
int dsdb_check_single_valued_link(const struct dsdb_attribute *attr,
				  const struct ldb_message_element *el)
{
	bool found_active = false;
	unsigned int i;

	if (!(attr->ldb_schema_attribute->flags & LDB_ATTR_FLAG_SINGLE_VALUE) ||
	    el->num_values < 2) {
		return LDB_SUCCESS;
	}

	for (i=0; i<el->num_values; i++) {
		if (!dsdb_dn_is_deleted_val(&el->values[i])) {
			if (found_active) {
				return LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS;
			}
			found_active = true;
		}
	}

	return LDB_SUCCESS;
}

/*
  check if an optional feature is enabled on our own NTDS DN

  Note that features can be marked as enabled in more than one
  place. For example, the recyclebin feature is marked as enabled both
  on the CN=Partitions,CN=Configurration object and on the NTDS DN of
  each DC in the forest. It seems likely that it is the job of the KCC
  to propogate between the two
 */
int dsdb_check_optional_feature(struct ldb_module *module, struct GUID op_feature_guid, bool *feature_enabled)
{
	TALLOC_CTX *tmp_ctx;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_result *res;
	struct ldb_dn *search_dn;
	struct GUID search_guid;
	const char *attrs[] = {"msDS-EnabledFeature", NULL};
	int ret;
	unsigned int i;
	struct ldb_message_element *el;
	struct ldb_dn *feature_dn;

	feature_dn = samdb_ntds_settings_dn(ldb_module_get_ctx(module));
	if (feature_dn == NULL) {
		return ldb_operr(ldb_module_get_ctx(module));
	}

	*feature_enabled = false;

	tmp_ctx = talloc_new(ldb);

	ret = dsdb_module_search_dn(module, tmp_ctx, &res, feature_dn, attrs, DSDB_FLAG_NEXT_MODULE, NULL);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb,
				"Could not find the feature object - dn: %s\n",
				ldb_dn_get_linearized(feature_dn));
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}
	if (res->msgs[0]->num_elements > 0) {
		const char *attrs2[] = {"msDS-OptionalFeatureGUID", NULL};

		el = ldb_msg_find_element(res->msgs[0],"msDS-EnabledFeature");

		for (i=0; i<el->num_values; i++) {
			search_dn = ldb_dn_from_ldb_val(tmp_ctx, ldb, &el->values[i]);

			ret = dsdb_module_search_dn(module, tmp_ctx, &res,
						    search_dn, attrs2, DSDB_FLAG_NEXT_MODULE, NULL);
			if (ret != LDB_SUCCESS) {
				ldb_asprintf_errstring(ldb,
						"Could no find object dn: %s\n",
						ldb_dn_get_linearized(search_dn));
				talloc_free(tmp_ctx);
				return LDB_ERR_OPERATIONS_ERROR;
			}

			search_guid = samdb_result_guid(res->msgs[0], "msDS-OptionalFeatureGUID");

			if (GUID_compare(&search_guid, &op_feature_guid) == 0) {
				*feature_enabled = true;
				break;
			}
		}
	}
	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

/*
  find the NTDS GUID from a computers DN record
 */
int dsdb_module_find_ntdsguid_for_computer(struct ldb_module *module,
					   TALLOC_CTX *mem_ctx,
					   struct ldb_dn *computer_dn,
					   struct GUID *ntds_guid,
					   struct ldb_request *parent)
{
	int ret;
	struct ldb_dn *dn;

	*ntds_guid = GUID_zero();

	ret = dsdb_module_reference_dn(module, mem_ctx, computer_dn,
				       "serverReferenceBL", &dn, parent);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	if (!ldb_dn_add_child_fmt(dn, "CN=NTDS Settings")) {
		talloc_free(dn);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	ret = dsdb_module_guid_by_dn(module, dn, ntds_guid, parent);
	talloc_free(dn);
	return ret;
}

/*
  find a 'reference' DN that points at another object
  (eg. serverReference, rIDManagerReference etc)
 */
int dsdb_module_reference_dn(struct ldb_module *module, TALLOC_CTX *mem_ctx, struct ldb_dn *base,
			     const char *attribute, struct ldb_dn **dn, struct ldb_request *parent)
{
	const char *attrs[2];
	struct ldb_result *res;
	int ret;

	attrs[0] = attribute;
	attrs[1] = NULL;

	ret = dsdb_module_search_dn(module, mem_ctx, &res, base, attrs,
	                            DSDB_FLAG_NEXT_MODULE | DSDB_SEARCH_SHOW_EXTENDED_DN, parent);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	*dn = ldb_msg_find_attr_as_dn(ldb_module_get_ctx(module),
				      mem_ctx, res->msgs[0], attribute);
	if (!*dn) {
		ldb_reset_err_string(ldb_module_get_ctx(module));
		talloc_free(res);
		return LDB_ERR_NO_SUCH_ATTRIBUTE;
	}

	talloc_free(res);
	return LDB_SUCCESS;
}

/*
  find the RID Manager$ DN via the rIDManagerReference attribute in the
  base DN
 */
int dsdb_module_rid_manager_dn(struct ldb_module *module, TALLOC_CTX *mem_ctx, struct ldb_dn **dn,
			       struct ldb_request *parent)
{
	return dsdb_module_reference_dn(module, mem_ctx,
					ldb_get_default_basedn(ldb_module_get_ctx(module)),
					"rIDManagerReference", dn, parent);
}

/*
  used to chain to the callers callback
 */
int dsdb_next_callback(struct ldb_request *req, struct ldb_reply *ares)
{
	struct ldb_request *up_req = talloc_get_type(req->context, struct ldb_request);

	talloc_steal(up_req, req);
	return up_req->callback(up_req, ares);
}

/*
  load the uSNHighest and the uSNUrgent attributes from the @REPLCHANGED
  object for a partition
 */
int dsdb_module_load_partition_usn(struct ldb_module *module, struct ldb_dn *dn,
				   uint64_t *uSN, uint64_t *urgent_uSN, struct ldb_request *parent)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_request *req;
	int ret;
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	struct dsdb_control_current_partition *p_ctrl;
	struct ldb_result *res;

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (!res) {
		talloc_free(tmp_ctx);
		return ldb_module_oom(module);
	}

	ret = ldb_build_search_req(&req, ldb, tmp_ctx,
				   ldb_dn_new(tmp_ctx, ldb, "@REPLCHANGED"),
				   LDB_SCOPE_BASE,
				   NULL, NULL,
				   NULL,
				   res, ldb_search_default_callback,
				   parent);
	LDB_REQ_SET_LOCATION(req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	p_ctrl = talloc(req, struct dsdb_control_current_partition);
	if (p_ctrl == NULL) {
		talloc_free(tmp_ctx);
		return ldb_module_oom(module);
	}
	p_ctrl->version = DSDB_CONTROL_CURRENT_PARTITION_VERSION;
	p_ctrl->dn = dn;


	ret = ldb_request_add_control(req,
				      DSDB_CONTROL_CURRENT_PARTITION_OID,
				      false, p_ctrl);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	/* Run the new request */
	ret = ldb_next_request(module, req);

	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}

	if (ret == LDB_ERR_NO_SUCH_OBJECT || ret == LDB_ERR_INVALID_DN_SYNTAX) {
		/* it hasn't been created yet, which means
		   an implicit value of zero */
		*uSN = 0;
		talloc_free(tmp_ctx);
		ldb_reset_err_string(ldb);
		return LDB_SUCCESS;
	}

	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (res->count != 1) {
		*uSN = 0;
		if (urgent_uSN) {
			*urgent_uSN = 0;
		}
	} else {
		*uSN = ldb_msg_find_attr_as_uint64(res->msgs[0], "uSNHighest", 0);
		if (urgent_uSN) {
			*urgent_uSN = ldb_msg_find_attr_as_uint64(res->msgs[0], "uSNUrgent", 0);
		}
	}

	talloc_free(tmp_ctx);

	return LDB_SUCCESS;
}

/*
  save uSNHighest and uSNUrgent attributes in the @REPLCHANGED object for a
  partition
 */
int dsdb_module_save_partition_usn(struct ldb_module *module, struct ldb_dn *dn,
				   uint64_t uSN, uint64_t urgent_uSN,
				   struct ldb_request *parent)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_request *req;
	struct ldb_message *msg;
	struct dsdb_control_current_partition *p_ctrl;
	int ret;
	struct ldb_result *res;

	msg = ldb_msg_new(module);
	if (msg == NULL) {
		return ldb_module_oom(module);
	}

	msg->dn = ldb_dn_new(msg, ldb, "@REPLCHANGED");
	if (msg->dn == NULL) {
		talloc_free(msg);
		return ldb_operr(ldb_module_get_ctx(module));
	}

	res = talloc_zero(msg, struct ldb_result);
	if (!res) {
		talloc_free(msg);
		return ldb_module_oom(module);
	}

	ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNHighest", uSN);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}
	msg->elements[0].flags = LDB_FLAG_MOD_REPLACE;

	/* urgent_uSN is optional so may not be stored */
	if (urgent_uSN) {
		ret = samdb_msg_add_uint64(ldb, msg, msg, "uSNUrgent",
					   urgent_uSN);
		if (ret != LDB_SUCCESS) {
			talloc_free(msg);
			return ret;
		}
		msg->elements[1].flags = LDB_FLAG_MOD_REPLACE;
	}


	p_ctrl = talloc(msg, struct dsdb_control_current_partition);
	if (p_ctrl == NULL) {
		talloc_free(msg);
		return ldb_oom(ldb);
	}
	p_ctrl->version = DSDB_CONTROL_CURRENT_PARTITION_VERSION;
	p_ctrl->dn = dn;
	ret = ldb_build_mod_req(&req, ldb, msg,
				msg,
				NULL,
				res,
				ldb_modify_default_callback,
				parent);
	LDB_REQ_SET_LOCATION(req);
again:
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	ret = ldb_request_add_control(req,
				      DSDB_CONTROL_CURRENT_PARTITION_OID,
				      false, p_ctrl);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	/* Run the new request */
	ret = ldb_next_request(module, req);

	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req->handle, LDB_WAIT_ALL);
	}
	if (ret == LDB_ERR_NO_SUCH_OBJECT) {
		ret = ldb_build_add_req(&req, ldb, msg,
					msg,
					NULL,
					res,
					ldb_modify_default_callback,
					parent);
		LDB_REQ_SET_LOCATION(req);
		goto again;
	}

	talloc_free(msg);

	return ret;
}

bool dsdb_module_am_system(struct ldb_module *module)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= talloc_get_type(ldb_get_opaque(ldb, "sessionInfo"), struct auth_session_info);
	return security_session_user_level(session_info, NULL) == SECURITY_SYSTEM;
}

bool dsdb_module_am_administrator(struct ldb_module *module)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= talloc_get_type(ldb_get_opaque(ldb, "sessionInfo"), struct auth_session_info);
	return security_session_user_level(session_info, NULL) == SECURITY_ADMINISTRATOR;
}

/*
  check if the recyclebin is enabled
 */
int dsdb_recyclebin_enabled(struct ldb_module *module, bool *enabled)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct GUID recyclebin_guid;
	int ret;

	GUID_from_string(DS_GUID_FEATURE_RECYCLE_BIN, &recyclebin_guid);

	ret = dsdb_check_optional_feature(module, recyclebin_guid, enabled);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb, "Could not verify if Recycle Bin is enabled \n");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	return LDB_SUCCESS;
}

int dsdb_msg_constrainted_update_int32(struct ldb_module *module,
				       struct ldb_message *msg,
				       const char *attr,
				       const int32_t *old_val,
				       const int32_t *new_val)
{
	struct ldb_message_element *el;
	int ret;
	char *vstring;

	if (old_val) {
		ret = ldb_msg_add_empty(msg, attr, LDB_FLAG_MOD_DELETE, &el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		el->num_values = 1;
		el->values = talloc_array(msg, struct ldb_val, el->num_values);
		if (!el->values) {
			return ldb_module_oom(module);
		}
		vstring = talloc_asprintf(el->values, "%ld", (long)*old_val);
		if (!vstring) {
			return ldb_module_oom(module);
		}
		*el->values = data_blob_string_const(vstring);
	}

	if (new_val) {
		ret = ldb_msg_add_empty(msg, attr, LDB_FLAG_MOD_ADD, &el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		el->num_values = 1;
		el->values = talloc_array(msg, struct ldb_val, el->num_values);
		if (!el->values) {
			return ldb_module_oom(module);
		}
		vstring = talloc_asprintf(el->values, "%ld", (long)*new_val);
		if (!vstring) {
			return ldb_module_oom(module);
		}
		*el->values = data_blob_string_const(vstring);
	}

	return LDB_SUCCESS;
}

int dsdb_msg_constrainted_update_uint32(struct ldb_module *module,
					struct ldb_message *msg,
					const char *attr,
					const uint32_t *old_val,
					const uint32_t *new_val)
{
	return dsdb_msg_constrainted_update_int32(module, msg, attr,
						  (const int32_t *)old_val,
						  (const int32_t *)new_val);
}

int dsdb_msg_constrainted_update_int64(struct ldb_module *module,
				       struct ldb_message *msg,
				       const char *attr,
				       const int64_t *old_val,
				       const int64_t *new_val)
{
	struct ldb_message_element *el;
	int ret;
	char *vstring;

	if (old_val) {
		ret = ldb_msg_add_empty(msg, attr, LDB_FLAG_MOD_DELETE, &el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		el->num_values = 1;
		el->values = talloc_array(msg, struct ldb_val, el->num_values);
		if (!el->values) {
			return ldb_module_oom(module);
		}
		vstring = talloc_asprintf(el->values, "%lld", (long long)*old_val);
		if (!vstring) {
			return ldb_module_oom(module);
		}
		*el->values = data_blob_string_const(vstring);
	}

	if (new_val) {
		ret = ldb_msg_add_empty(msg, attr, LDB_FLAG_MOD_ADD, &el);
		if (ret != LDB_SUCCESS) {
			return ret;
		}
		el->num_values = 1;
		el->values = talloc_array(msg, struct ldb_val, el->num_values);
		if (!el->values) {
			return ldb_module_oom(module);
		}
		vstring = talloc_asprintf(el->values, "%lld", (long long)*new_val);
		if (!vstring) {
			return ldb_module_oom(module);
		}
		*el->values = data_blob_string_const(vstring);
	}

	return LDB_SUCCESS;
}

int dsdb_msg_constrainted_update_uint64(struct ldb_module *module,
					struct ldb_message *msg,
					const char *attr,
					const uint64_t *old_val,
					const uint64_t *new_val)
{
	return dsdb_msg_constrainted_update_int64(module, msg, attr,
						  (const int64_t *)old_val,
						  (const int64_t *)new_val);
}

/*
  update an int32 attribute safely via a constrained delete/add
 */
int dsdb_module_constrainted_update_int32(struct ldb_module *module,
					  struct ldb_dn *dn,
					  const char *attr,
					  const int32_t *old_val,
					  const int32_t *new_val,
					  struct ldb_request *parent)
{
	struct ldb_message *msg;
	int ret;

	msg = ldb_msg_new(module);
	msg->dn = dn;

	ret = dsdb_msg_constrainted_update_int32(module,
						 msg, attr,
						 old_val,
						 new_val);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	ret = dsdb_module_modify(module, msg, DSDB_FLAG_NEXT_MODULE, parent);
	talloc_free(msg);
	return ret;
}

int dsdb_module_constrainted_update_uint32(struct ldb_module *module,
					   struct ldb_dn *dn,
					   const char *attr,
					   const uint32_t *old_val,
					   const uint32_t *new_val,
					   struct ldb_request *parent)
{
	return dsdb_module_constrainted_update_int32(module, dn, attr,
						     (const int32_t *)old_val,
						     (const int32_t *)new_val, parent);
}

/*
  update an int64 attribute safely via a constrained delete/add
 */
int dsdb_module_constrainted_update_int64(struct ldb_module *module,
					  struct ldb_dn *dn,
					  const char *attr,
					  const int64_t *old_val,
					  const int64_t *new_val,
					  struct ldb_request *parent)
{
	struct ldb_message *msg;
	int ret;

	msg = ldb_msg_new(module);
	msg->dn = dn;

	ret = dsdb_msg_constrainted_update_int64(module,
						 msg, attr,
						 old_val,
						 new_val);
	if (ret != LDB_SUCCESS) {
		talloc_free(msg);
		return ret;
	}

	ret = dsdb_module_modify(module, msg, DSDB_FLAG_NEXT_MODULE, parent);
	talloc_free(msg);
	return ret;
}

int dsdb_module_constrainted_update_uint64(struct ldb_module *module,
					   struct ldb_dn *dn,
					   const char *attr,
					   const uint64_t *old_val,
					   const uint64_t *new_val,
					   struct ldb_request *parent)
{
	return dsdb_module_constrainted_update_int64(module, dn, attr,
						     (const int64_t *)old_val,
						     (const int64_t *)new_val,
						     parent);
}


const struct ldb_val *dsdb_module_find_dsheuristics(struct ldb_module *module,
						    TALLOC_CTX *mem_ctx, struct ldb_request *parent)
{
	int ret;
	struct ldb_dn *new_dn;
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	static const char *attrs[] = { "dSHeuristics", NULL };
	struct ldb_result *res;

	new_dn = ldb_dn_copy(mem_ctx, ldb_get_config_basedn(ldb));
	if (!ldb_dn_add_child_fmt(new_dn,
				   "CN=Directory Service,CN=Windows NT,CN=Services")) {
		talloc_free(new_dn);
		return NULL;
	}
	ret = dsdb_module_search_dn(module, mem_ctx, &res,
				    new_dn,
				    attrs,
				    DSDB_FLAG_NEXT_MODULE,
				    parent);
	if (ret == LDB_SUCCESS && res->count == 1) {
		talloc_free(new_dn);
		return ldb_msg_find_ldb_val(res->msgs[0],
					    "dSHeuristics");
	}
	talloc_free(new_dn);
	return NULL;
}

bool dsdb_block_anonymous_ops(struct ldb_module *module, struct ldb_request *parent)
{
	TALLOC_CTX *tmp_ctx = talloc_new(module);
	bool result;
	const struct ldb_val *hr_val = dsdb_module_find_dsheuristics(module,
								     tmp_ctx, parent);
	if (hr_val == NULL || hr_val->length < DS_HR_BLOCK_ANONYMOUS_OPS) {
		result = true;
	} else if (hr_val->data[DS_HR_BLOCK_ANONYMOUS_OPS -1] == '2') {
		result = false;
	} else {
		result = true;
	}

	talloc_free(tmp_ctx);
	return result;
}

bool dsdb_user_password_support(struct ldb_module *module,
				TALLOC_CTX *mem_ctx,
				struct ldb_request *parent)
{
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	bool result;
	const struct ldb_val *hr_val = dsdb_module_find_dsheuristics(module,
								     tmp_ctx,
								     parent);
	if (hr_val == NULL || hr_val->length < DS_HR_USER_PASSWORD_SUPPORT) {
		result = false;
	} else if ((hr_val->data[DS_HR_USER_PASSWORD_SUPPORT -1] == '2') ||
		   (hr_val->data[DS_HR_USER_PASSWORD_SUPPORT -1] == '0')) {
		result = false;
	} else {
		result = true;
	}

	talloc_free(tmp_ctx);
	return result;
}

/*
  show the chain of requests, useful for debugging async requests
 */
void dsdb_req_chain_debug(struct ldb_request *req, int level)
{
	char *s = ldb_module_call_chain(req, req);
	DEBUG(level, ("%s\n", s));
	talloc_free(s);
}

/*
 * Gets back a single-valued attribute by the rules of the DSDB triggers when
 * performing a modify operation.
 *
 * In order that the constraint checking by the "objectclass_attrs" LDB module
 * does work properly, the change request should remain similar or only be
 * enhanced (no other modifications as deletions, variations).
 */
struct ldb_message_element *dsdb_get_single_valued_attr(const struct ldb_message *msg,
							const char *attr_name,
							enum ldb_request_type operation)
{
	struct ldb_message_element *el = NULL;
	unsigned int i;

	/* We've to walk over all modification entries and consider the last
	 * non-delete one which belongs to "attr_name".
	 *
	 * If "el" is NULL afterwards then that means there was no interesting
	 * change entry. */
	for (i = 0; i < msg->num_elements; i++) {
		if (ldb_attr_cmp(msg->elements[i].name, attr_name) == 0) {
			if ((operation == LDB_MODIFY) &&
			    (LDB_FLAG_MOD_TYPE(msg->elements[i].flags)
						== LDB_FLAG_MOD_DELETE)) {
				continue;
			}
			el = &msg->elements[i];
		}
	}

	return el;
}

/*
 * This function determines the (last) structural or 88 object class of a passed
 * "objectClass" attribute - per MS-ADTS 3.1.1.1.4 this is the last value.
 * Without schema this does not work and hence NULL is returned.
 */
const struct dsdb_class *dsdb_get_last_structural_class(const struct dsdb_schema *schema,
							const struct ldb_message_element *element)
{
	const struct dsdb_class *last_class;

	if (schema == NULL) {
		return NULL;
	}

	if (element->num_values == 0) {
		return NULL;
	}

	last_class = dsdb_class_by_lDAPDisplayName_ldb_val(schema,
							   &element->values[element->num_values-1]);
	if (last_class == NULL) {
		return NULL;
	}
	if (last_class->objectClassCategory > 1) {
		return NULL;
	}

	return last_class;
}