/* 
   Unix SMB/CIFS implementation.

   rootDSE ldb module

   Copyright (C) Andrew Tridgell 2005
   Copyright (C) Simo Sorce 2005-2008
   
   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 "lib/ldb/include/ldb.h"
#include "lib/ldb/include/ldb_module.h"
#include "system/time.h"
#include "dsdb/samdb/samdb.h"
#include "version.h"
#include "dsdb/samdb/ldb_modules/util.h"
#include "libcli/security/security.h"
#include "librpc/ndr/libndr.h"
#include "auth/auth.h"

struct private_data {
	unsigned int num_controls;
	char **controls;
	unsigned int num_partitions;
	struct ldb_dn **partitions;
};

/*
  return 1 if a specific attribute has been requested
*/
static int do_attribute(const char * const *attrs, const char *name)
{
	return attrs == NULL ||
		ldb_attr_in_list(attrs, name) ||
		ldb_attr_in_list(attrs, "*");
}

static int do_attribute_explicit(const char * const *attrs, const char *name)
{
	return attrs != NULL && ldb_attr_in_list(attrs, name);
}


/*
  expand a DN attribute to include extended DN information if requested
 */
static int expand_dn_in_message(struct ldb_module *module, struct ldb_message *msg,
				const char *attrname, struct ldb_control *edn_control,
				struct ldb_request *req)
{
	struct ldb_dn *dn, *dn2;
	struct ldb_val *v;
	int ret;
	struct ldb_request *req2;
	char *dn_string;
	const char *no_attrs[] = { NULL };
	struct ldb_result *res;
	struct ldb_extended_dn_control *edn;
	TALLOC_CTX *tmp_ctx = talloc_new(req);
	struct ldb_context *ldb;
	int edn_type = 0;

	ldb = ldb_module_get_ctx(module);

	edn = talloc_get_type(edn_control->data, struct ldb_extended_dn_control);
	if (edn) {
		edn_type = edn->type;
	}

	v = discard_const_p(struct ldb_val, ldb_msg_find_ldb_val(msg, attrname));
	if (v == NULL) {
		talloc_free(tmp_ctx);
		return LDB_SUCCESS;
	}

	dn_string = talloc_strndup(tmp_ctx, (const char *)v->data, v->length);
	if (dn_string == NULL) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	res = talloc_zero(tmp_ctx, struct ldb_result);
	if (res == NULL) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	dn = ldb_dn_new(tmp_ctx, ldb, dn_string);
	if (!ldb_dn_validate(dn)) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	ret = ldb_build_search_req(&req2, ldb, tmp_ctx,
				   dn,
				   LDB_SCOPE_BASE,
				   NULL,
				   no_attrs,
				   NULL,
				   res, ldb_search_default_callback,
				   req);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}


	ret = ldb_request_add_control(req2,
				      LDB_CONTROL_EXTENDED_DN_OID,
				      edn_control->critical, edn);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	ret = ldb_next_request(module, req2);
	if (ret == LDB_SUCCESS) {
		ret = ldb_wait(req2->handle, LDB_WAIT_ALL);
	}
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	if (!res || res->count != 1) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	dn2 = res->msgs[0]->dn;

	v->data = (uint8_t *)ldb_dn_get_extended_linearized(msg->elements, dn2, edn_type);
	v->length = strlen((char *)v->data);

	if (v->data == NULL) {
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	talloc_free(tmp_ctx);

	return LDB_SUCCESS;
}	
			

/*
  add dynamically generated attributes to rootDSE result
*/
static int rootdse_add_dynamic(struct ldb_module *module, struct ldb_message *msg, 
			       const char * const *attrs, struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct private_data *priv = talloc_get_type(ldb_module_get_private(module), struct private_data);
	char **server_sasl;
	const struct dsdb_schema *schema;
	int *val;
	struct ldb_control *edn_control;
	const char *dn_attrs[] = {
		"configurationNamingContext",
		"defaultNamingContext",
		"dsServiceName",
		"rootDomainNamingContext",
		"schemaNamingContext",
		"serverName",
		NULL
	};

	ldb = ldb_module_get_ctx(module);
	schema = dsdb_get_schema(ldb, NULL);

	msg->dn = ldb_dn_new(msg, ldb, NULL);

	/* don't return the distinduishedName, cn and name attributes */
	ldb_msg_remove_attr(msg, "distinguishedName");
	ldb_msg_remove_attr(msg, "cn");
	ldb_msg_remove_attr(msg, "name");

	if (do_attribute(attrs, "currentTime")) {
		if (ldb_msg_add_steal_string(msg, "currentTime", 
					     ldb_timestring(msg, time(NULL))) != 0) {
			goto failed;
		}
	}

	if (priv && do_attribute(attrs, "supportedControl")) {
		unsigned int i;
		for (i = 0; i < priv->num_controls; i++) {
			char *control = talloc_strdup(msg, priv->controls[i]);
			if (!control) {
				goto failed;
			}
			if (ldb_msg_add_steal_string(msg, "supportedControl",
						     control) != 0) {
				goto failed;
 			}
 		}
 	}

	if (priv && do_attribute(attrs, "namingContexts")) {
		unsigned int i;
		for (i = 0; i < priv->num_partitions; i++) {
			struct ldb_dn *dn = priv->partitions[i];
			if (ldb_msg_add_steal_string(msg, "namingContexts",
						     ldb_dn_alloc_linearized(msg, dn)) != 0) {
				goto failed;
 			}
 		}
	}

	server_sasl = talloc_get_type(ldb_get_opaque(ldb, "supportedSASLMechanims"), 
				       char *);
	if (server_sasl && do_attribute(attrs, "supportedSASLMechanisms")) {
		unsigned int i;
		for (i = 0; server_sasl && server_sasl[i]; i++) {
			char *sasl_name = talloc_strdup(msg, server_sasl[i]);
			if (!sasl_name) {
				goto failed;
			}
			if (ldb_msg_add_steal_string(msg, "supportedSASLMechanisms",
						     sasl_name) != 0) {
				goto failed;
			}
		}
	}

	if (do_attribute(attrs, "highestCommittedUSN")) {
		uint64_t seq_num;
		int ret = ldb_sequence_number(ldb, LDB_SEQ_HIGHEST_SEQ, &seq_num);
		if (ret == LDB_SUCCESS) {
			if (ldb_msg_add_fmt(msg, "highestCommittedUSN", 
					    "%llu", (unsigned long long)seq_num) != 0) {
				goto failed;
			}
		}
	}

	if (schema && do_attribute_explicit(attrs, "dsSchemaAttrCount")) {
		struct dsdb_attribute *cur;
		unsigned int n = 0;

		for (cur = schema->attributes; cur; cur = cur->next) {
			n++;
		}

		if (ldb_msg_add_fmt(msg, "dsSchemaAttrCount", 
				    "%u", n) != 0) {
			goto failed;
		}
	}

	if (schema && do_attribute_explicit(attrs, "dsSchemaClassCount")) {
		struct dsdb_class *cur;
		unsigned int n = 0;

		for (cur = schema->classes; cur; cur = cur->next) {
			n++;
		}

		if (ldb_msg_add_fmt(msg, "dsSchemaClassCount", 
				    "%u", n) != 0) {
			goto failed;
		}
	}

	if (schema && do_attribute_explicit(attrs, "dsSchemaPrefixCount")) {
		if (ldb_msg_add_fmt(msg, "dsSchemaPrefixCount", 
				    "%u", schema->prefixmap->length) != 0) {
			goto failed;
		}
	}

	if (do_attribute_explicit(attrs, "validFSMOs")) {
		const struct dsdb_naming_fsmo *naming_fsmo;
		const struct dsdb_pdc_fsmo *pdc_fsmo;
		const char *dn_str;

		if (schema && schema->fsmo.we_are_master) {
			dn_str = ldb_dn_get_linearized(ldb_get_schema_basedn(ldb));
			if (dn_str && dn_str[0]) {
				if (ldb_msg_add_fmt(msg, "validFSMOs", "%s", dn_str) != 0) {
					goto failed;
				}
			}
		}

		naming_fsmo = talloc_get_type(ldb_get_opaque(ldb, "dsdb_naming_fsmo"),
					      struct dsdb_naming_fsmo);
		if (naming_fsmo && naming_fsmo->we_are_master) {
			dn_str = ldb_dn_get_linearized(samdb_partitions_dn(ldb, msg));
			if (dn_str && dn_str[0]) {
				if (ldb_msg_add_fmt(msg, "validFSMOs", "%s", dn_str) != 0) {
					goto failed;
				}
			}
		}

		pdc_fsmo = talloc_get_type(ldb_get_opaque(ldb, "dsdb_pdc_fsmo"),
					   struct dsdb_pdc_fsmo);
		if (pdc_fsmo && pdc_fsmo->we_are_master) {
			dn_str = ldb_dn_get_linearized(ldb_get_default_basedn(ldb));
			if (dn_str && dn_str[0]) {
				if (ldb_msg_add_fmt(msg, "validFSMOs", "%s", dn_str) != 0) {
					goto failed;
				}
			}
		}
	}

	if (do_attribute_explicit(attrs, "vendorVersion")) {
		if (ldb_msg_add_fmt(msg, "vendorVersion", 
				    "%s", SAMBA_VERSION_STRING) != 0) {
			goto failed;
		}
	}

	if (priv && do_attribute(attrs, "domainFunctionality")) {
		if (ldb_msg_add_fmt(msg, "domainFunctionality", 
				    "%d", dsdb_functional_level(ldb)) != 0) {
			goto failed;
		}
	}

	if (priv && do_attribute(attrs, "forestFunctionality")
	    && (val = talloc_get_type(ldb_get_opaque(ldb, "forestFunctionality"), int))) {
		if (ldb_msg_add_fmt(msg, "forestFunctionality", 
				    "%d", *val) != 0) {
			goto failed;
		}
	}

	if (priv && do_attribute(attrs, "domainControllerFunctionality")
	    && (val = talloc_get_type(ldb_get_opaque(ldb, "domainControllerFunctionality"), int))) {
		if (ldb_msg_add_fmt(msg, "domainControllerFunctionality", 
				    "%d", *val) != 0) {
			goto failed;
		}
	}

	edn_control = ldb_request_get_control(req, LDB_CONTROL_EXTENDED_DN_OID);

	/* if the client sent us the EXTENDED_DN control then we need
	   to expand the DNs to have GUID and SID. W2K8 join relies on
	   this */
	if (edn_control) {
		unsigned int i;
		int ret;
		for (i=0; dn_attrs[i]; i++) {
			if (!do_attribute(attrs, dn_attrs[i])) continue;
			ret = expand_dn_in_message(module, msg, dn_attrs[i],
						   edn_control, req);
			if (ret != LDB_SUCCESS) {
				DEBUG(0,(__location__ ": Failed to expand DN in rootDSE for %s\n",
					 dn_attrs[i]));
				goto failed;
			}
		}
	}

	if (do_attribute(attrs, "isGlobalCatalogReady")) {
		/* MS-ADTS 3.1.1.3.2.10
		   Note, we should only return true here is we have
		   completed at least one synchronisation. As both
		   provision and vampire do a full sync, this means we
		   can return true is the gc bit is set in the NTDSDSA
		   options */
		if (ldb_msg_add_fmt(msg, "isGlobalCatalogReady",
				    "%s", samdb_is_gc(ldb)?"TRUE":"FALSE") != 0) {
			goto failed;
		}
	}

	if (do_attribute_explicit(attrs, "tokenGroups")) {
		unsigned int i;
		/* Obtain the user's session_info */
		struct auth_session_info *session_info
			= (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
		if (session_info && session_info->security_token) {
			/* The list of groups this user is in */
			for (i = 0; i < session_info->security_token->num_sids; i++) {
				if (samdb_msg_add_dom_sid(ldb, msg, msg,
							  "tokenGroups",
							  session_info->security_token->sids[i]) != 0) {
					goto failed;
				}
			}
		}
	}

	/* TODO: lots more dynamic attributes should be added here */

	return LDB_SUCCESS;

failed:
	return LDB_ERR_OPERATIONS_ERROR;
}

/*
  handle search requests
*/

struct rootdse_context {
	struct ldb_module *module;
	struct ldb_request *req;
};

static struct rootdse_context *rootdse_init_context(struct ldb_module *module,
						    struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct rootdse_context *ac;

	ldb = ldb_module_get_ctx(module);

	ac = talloc_zero(req, struct rootdse_context);
	if (ac == NULL) {
		ldb_set_errstring(ldb, "Out of Memory");
		return NULL;
	}

	ac->module = module;
	ac->req = req;

	return ac;
}

static int rootdse_callback(struct ldb_request *req, struct ldb_reply *ares)
{
	struct rootdse_context *ac;
	int ret;

	ac = talloc_get_type(req->context, struct rootdse_context);

	if (!ares) {
		return ldb_module_done(ac->req, NULL, NULL,
					LDB_ERR_OPERATIONS_ERROR);
	}
	if (ares->error != LDB_SUCCESS) {
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}

	switch (ares->type) {
	case LDB_REPLY_ENTRY:
		/*
		 * if the client explicit asks for the 'netlogon' attribute
		 * the reply_entry needs to be skipped
		 */
		if (ac->req->op.search.attrs &&
		    ldb_attr_in_list(ac->req->op.search.attrs, "netlogon")) {
			talloc_free(ares);
			return LDB_SUCCESS;
		}

		/* for each record returned post-process to add any dynamic
		   attributes that have been asked for */
		ret = rootdse_add_dynamic(ac->module, ares->message,
					  ac->req->op.search.attrs, ac->req);
		if (ret != LDB_SUCCESS) {
			talloc_free(ares);
			return ldb_module_done(ac->req, NULL, NULL, ret);
		}

		return ldb_module_send_entry(ac->req, ares->message, ares->controls);

	case LDB_REPLY_REFERRAL:
		/* should we allow the backend to return referrals in this case
		 * ?? */
		break;

	case LDB_REPLY_DONE:
		return ldb_module_done(ac->req, ares->controls,
					ares->response, ares->error);
	}

	talloc_free(ares);
	return LDB_SUCCESS;
}

static int rootdse_search(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;
	struct rootdse_context *ac;
	struct ldb_request *down_req;
	int ret;

	ldb = ldb_module_get_ctx(module);

	/* see if its for the rootDSE - only a base search on the "" DN qualifies */
	if (!(req->op.search.scope == LDB_SCOPE_BASE && ldb_dn_is_null(req->op.search.base))) {
		/* Otherwise, pass down to the rest of the stack */
		return ldb_next_request(module, req);
	}

	ac = rootdse_init_context(module, req);
	if (ac == NULL) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	/* in our db we store the rootDSE with a DN of @ROOTDSE */
	ret = ldb_build_search_req(&down_req, ldb, ac,
					ldb_dn_new(ac, ldb, "@ROOTDSE"),
					LDB_SCOPE_BASE,
					NULL,
					req->op.search.attrs,
					NULL,/* for now skip the controls from the client */
					ac, rootdse_callback,
					req);
	if (ret != LDB_SUCCESS) {
		return ret;
	}

	return ldb_next_request(module, down_req);
}

static int rootdse_register_control(struct ldb_module *module, struct ldb_request *req)
{
	struct private_data *priv = talloc_get_type(ldb_module_get_private(module), struct private_data);
	char **list;

	list = talloc_realloc(priv, priv->controls, char *, priv->num_controls + 1);
	if (!list) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	list[priv->num_controls] = talloc_strdup(list, req->op.reg_control.oid);
	if (!list[priv->num_controls]) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	priv->num_controls += 1;
	priv->controls = list;

	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}

static int rootdse_register_partition(struct ldb_module *module, struct ldb_request *req)
{
	struct private_data *priv = talloc_get_type(ldb_module_get_private(module), struct private_data);
	struct ldb_dn **list;

	list = talloc_realloc(priv, priv->partitions, struct ldb_dn *, priv->num_partitions + 1);
	if (!list) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	list[priv->num_partitions] = ldb_dn_copy(list, req->op.reg_partition.dn);
	if (!list[priv->num_partitions]) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	priv->num_partitions += 1;
	priv->partitions = list;

	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
}


static int rootdse_request(struct ldb_module *module, struct ldb_request *req)
{
	switch (req->operation) {

	case LDB_REQ_REGISTER_CONTROL:
		return rootdse_register_control(module, req);
	case LDB_REQ_REGISTER_PARTITION:
		return rootdse_register_partition(module, req);

	default:
		break;
	}
	return ldb_next_request(module, req);
}

static int rootdse_init(struct ldb_module *module)
{
	int ret;
	struct ldb_context *ldb;
	struct ldb_result *res;
	struct private_data *data;
	const char *attrs[] = { "msDS-Behavior-Version", NULL };
	const char *ds_attrs[] = { "dsServiceName", NULL };
	TALLOC_CTX *mem_ctx;

	ldb = ldb_module_get_ctx(module);

	data = talloc_zero(module, struct private_data);
	if (data == NULL) {
		ldb_oom(ldb);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	data->num_controls = 0;
	data->controls = NULL;
	data->num_partitions = 0;
	data->partitions = NULL;
	ldb_module_set_private(module, data);

	ldb_set_default_dns(ldb);

	ret = ldb_next_init(module);

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

	mem_ctx = talloc_new(data);
	if (!mem_ctx) {
		ldb_oom(ldb);
		return LDB_ERR_OPERATIONS_ERROR;
	}

	/* Now that the partitions are set up, do a search for:
	   - domainControllerFunctionality
	   - domainFunctionality
	   - forestFunctionality

	   Then stuff these values into an opaque
	*/
	ret = ldb_search(ldb, mem_ctx, &res,
			 ldb_get_default_basedn(ldb),
			 LDB_SCOPE_BASE, attrs, NULL);
	if (ret == LDB_SUCCESS && res->count == 1) {
		int domain_behaviour_version
			= ldb_msg_find_attr_as_int(res->msgs[0], 
						   "msDS-Behavior-Version", -1);
		if (domain_behaviour_version != -1) {
			int *val = talloc(ldb, int);
			if (!val) {
				ldb_oom(ldb);
				talloc_free(mem_ctx);
				return LDB_ERR_OPERATIONS_ERROR;
			}
			*val = domain_behaviour_version;
			ret = ldb_set_opaque(ldb, "domainFunctionality", val);
			if (ret != LDB_SUCCESS) {
				talloc_free(mem_ctx);
				return ret;
			}
		}
	}

	ret = ldb_search(ldb, mem_ctx, &res,
			 samdb_partitions_dn(ldb, mem_ctx),
			 LDB_SCOPE_BASE, attrs, NULL);
	if (ret == LDB_SUCCESS && res->count == 1) {
		int forest_behaviour_version
			= ldb_msg_find_attr_as_int(res->msgs[0], 
						   "msDS-Behavior-Version", -1);
		if (forest_behaviour_version != -1) {
			int *val = talloc(ldb, int);
			if (!val) {
				ldb_oom(ldb);
				talloc_free(mem_ctx);
				return LDB_ERR_OPERATIONS_ERROR;
			}
			*val = forest_behaviour_version;
			ret = ldb_set_opaque(ldb, "forestFunctionality", val);
			if (ret != LDB_SUCCESS) {
				talloc_free(mem_ctx);
				return ret;
			}
		}
	}

	ret = ldb_search(ldb, mem_ctx, &res,
			 ldb_dn_new(mem_ctx, ldb, ""),
			 LDB_SCOPE_BASE, ds_attrs, NULL);
	if (ret == LDB_SUCCESS && res->count == 1) {
		struct ldb_dn *ds_dn
			= ldb_msg_find_attr_as_dn(ldb, mem_ctx, res->msgs[0], 
						  "dsServiceName");
		if (ds_dn) {
			ret = ldb_search(ldb, mem_ctx, &res, ds_dn, 
					 LDB_SCOPE_BASE, attrs, NULL);
			if (ret == LDB_SUCCESS && res->count == 1) {
				int domain_controller_behaviour_version
					= ldb_msg_find_attr_as_int(res->msgs[0], 
								   "msDS-Behavior-Version", -1);
				if (domain_controller_behaviour_version != -1) {
					int *val = talloc(ldb, int);
					if (!val) {
						ldb_oom(ldb);
						talloc_free(mem_ctx);
					return LDB_ERR_OPERATIONS_ERROR;
					}
					*val = domain_controller_behaviour_version;
					ret = ldb_set_opaque(ldb, 
							     "domainControllerFunctionality", val);
					if (ret != LDB_SUCCESS) {
						talloc_free(mem_ctx);
						return ret;
					}
				}
			}
		}
	}

	talloc_free(mem_ctx);
	
	return LDB_SUCCESS;
}

/*
 * This function gets the string SCOPE_DN:OPTIONAL_FEATURE_GUID and parse it
 * to a DN and a GUID object
 */
static int get_optional_feature_dn_guid(struct ldb_request *req, struct ldb_context *ldb,
						TALLOC_CTX *mem_ctx,
						struct ldb_dn **op_feature_scope_dn,
						struct GUID *op_feature_guid)
{
	const struct ldb_message *msg = req->op.mod.message;
	const char *ldb_val_str;
	char *dn, *guid;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	NTSTATUS status;

	ldb_val_str = ldb_msg_find_attr_as_string(msg, "enableOptionalFeature", NULL);
	if (!ldb_val_str) {
		ldb_asprintf_errstring(ldb,
				       "rootdse: unable to find enableOptionalFeature\n");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	guid = strchr(ldb_val_str, ':');
	if (!guid) {
		ldb_asprintf_errstring(ldb,
				       "rootdse: unable to find GUID in enableOptionalFeature\n");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	status = GUID_from_string(guid+1, op_feature_guid);
	if (!NT_STATUS_IS_OK(status)) {
		ldb_asprintf_errstring(ldb,
				       "rootdse: bad GUID in enableOptionalFeature\n");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	dn = talloc_strndup(tmp_ctx, ldb_val_str, guid-ldb_val_str);
	if (!dn) {
		ldb_asprintf_errstring(ldb,
				       "rootdse: bad DN in enableOptionalFeature\n");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	*op_feature_scope_dn = ldb_dn_new(mem_ctx, ldb, dn);

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

/*
 * This function gets the OPTIONAL_FEATURE_GUID and looks for the optional feature
 * ldb_message object.
 */
static int dsdb_find_optional_feature(struct ldb_module *module, struct ldb_context *ldb,
				TALLOC_CTX *mem_ctx, struct GUID op_feature_guid, struct ldb_message **msg)
{
	struct ldb_result *res;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	int ret;

	ret = dsdb_module_search(module, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE,
				NULL,
				DSDB_SEARCH_SEARCH_ALL_PARTITIONS,
				 "(&(objectClass=msDS-OptionalFeature)"
				 "(msDS-OptionalFeatureGUID=%s))",GUID_string(tmp_ctx, &op_feature_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,
				"More than one object found matching optional feature GUID %s\n",
				GUID_string(tmp_ctx, &op_feature_guid));
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}

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

	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

static int rootdse_enable_recycle_bin(struct ldb_module *module,struct ldb_context *ldb,
			TALLOC_CTX *mem_ctx, struct ldb_dn *op_feature_scope_dn,
			struct ldb_message *op_feature_msg)
{
	int ret;
	const int domain_func_level = dsdb_functional_level(ldb);
	struct ldb_dn *ntds_settings_dn;
	TALLOC_CTX *tmp_ctx;
	unsigned int el_count = 0;
	struct ldb_message *msg;

	ret = ldb_msg_find_attr_as_int(op_feature_msg, "msDS-RequiredForestBehaviorVersion", 0);
	if (domain_func_level < ret){
		ldb_asprintf_errstring(ldb,
						       "rootdse: Domain functional level must be at least %d\n",
						       ret);
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	tmp_ctx = talloc_new(mem_ctx);
	ntds_settings_dn = samdb_ntds_settings_dn(ldb);
	if (!ntds_settings_dn) {
		ldb_asprintf_errstring(ldb,
				__location__ ": Failed to find NTDS settings DN\n");
		ret = LDB_ERR_OPERATIONS_ERROR;
		talloc_free(tmp_ctx);
		return ret;
	}

	ntds_settings_dn = ldb_dn_copy(tmp_ctx, ntds_settings_dn);
	if (!ntds_settings_dn) {
		DEBUG(0, (__location__ ": Failed to copy NTDS settings DN\n"));
		ret = LDB_ERR_OPERATIONS_ERROR;
		talloc_free(tmp_ctx);
		return ret;
	}

	msg = ldb_msg_new(tmp_ctx);
	msg->dn = ntds_settings_dn;

	ldb_msg_add_linearized_dn(msg, "msDS-EnabledFeature", op_feature_msg->dn);
	msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;

	ret = dsdb_module_modify(module, msg, 0);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb,
				"rootdse_enable_recycle_bin: Failed to modify object %s - %s",
				ldb_dn_get_linearized(ntds_settings_dn), ldb_errstring(ldb));
		talloc_free(tmp_ctx);
		return ret;
	}

	msg->dn = op_feature_scope_dn;
	ret = dsdb_module_modify(module, msg, 0);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb, "rootdse_enable_recycle_bin: Failed to modify object %s - %s",
				       ldb_dn_get_linearized(op_feature_scope_dn), ldb_errstring(ldb));
		talloc_free(tmp_ctx);
		return ret;
	}

	return LDB_SUCCESS;
}

static int rootdse_enableoptionalfeature(struct ldb_module *module, struct ldb_request *req)
{
	/*
	  steps:
	       - check for system (only system can enable features)
	       - extract GUID from the request
	       - find the feature object
	       - check functional level, must be at least msDS-RequiredForestBehaviorVersion
	       - check if it is already enabled (if enabled return LDAP_ATTRIBUTE_OR_VALUE_EXISTS) - probably not needed, just return error from the add/modify
	       - add/modify objects (see ntdsconnection code for an example)
	 */

	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct GUID op_feature_guid;
	struct ldb_dn *op_feature_scope_dn;
	struct ldb_message *op_feature_msg;
	struct auth_session_info *session_info =
				(struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
	TALLOC_CTX *tmp_ctx = talloc_new(ldb);
	int ret;
	const char *guid_string;

	if (security_session_user_level(session_info, NULL) != SECURITY_SYSTEM) {
		ldb_asprintf_errstring(ldb, "rootdse: Insufficient rights for enableoptionalfeature");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	ret = get_optional_feature_dn_guid(req, ldb, tmp_ctx, &op_feature_scope_dn, &op_feature_guid);
	if (ret != LDB_SUCCESS) {
		talloc_free(tmp_ctx);
		return ret;
	}

	guid_string = GUID_string(tmp_ctx, &op_feature_guid);
	if (!guid_string) {
		ldb_asprintf_errstring(ldb, "rootdse: bad optional feature GUID");
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}

	ret = dsdb_find_optional_feature(module, ldb, tmp_ctx, op_feature_guid, &op_feature_msg);
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb, "rootdse: unable to find optional feature for %s - %s",
						       guid_string, ldb_errstring(ldb));
		talloc_free(tmp_ctx);
		return ret;
	}

	if (strcasecmp(DS_GUID_FEATURE_RECYCLE_BIN, guid_string) == 0) {
			ret = rootdse_enable_recycle_bin(module, ldb,
							 tmp_ctx, op_feature_scope_dn,
							 op_feature_msg);
	} else {
		ldb_asprintf_errstring(ldb, "rootdse: unknown optional feature %s",
				       guid_string);
		talloc_free(tmp_ctx);
		return LDB_ERR_UNWILLING_TO_PERFORM;
	}
	if (ret != LDB_SUCCESS) {
		ldb_asprintf_errstring(ldb, "rootdse: failed to set optional feature for %s - %s",
				       guid_string, ldb_errstring(ldb));
		talloc_free(tmp_ctx);
		return ret;
	}

	talloc_free(tmp_ctx);
	return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);;
}

static int rootdse_schemaupdatenow(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct ldb_result *ext_res;
	int ret;
	struct ldb_dn *schema_dn;

	schema_dn = ldb_get_schema_basedn(ldb);
	if (!schema_dn) {
		ldb_reset_err_string(ldb);
		ldb_debug(ldb, LDB_DEBUG_WARNING,
			  "rootdse_modify: no schema dn present: (skip ldb_extended call)\n");
		return ldb_next_request(module, req);
	}

	ret = ldb_extended(ldb, DSDB_EXTENDED_SCHEMA_UPDATE_NOW_OID, schema_dn, &ext_res);
	if (ret != LDB_SUCCESS) {
		return LDB_ERR_OPERATIONS_ERROR;
	}

	talloc_free(ext_res);
	return ldb_module_done(req, NULL, NULL, ret);
}

static int rootdse_modify(struct ldb_module *module, struct ldb_request *req)
{
	struct ldb_context *ldb;

	/*
		If dn is not "" we should let it pass through
	*/
	if (!ldb_dn_is_null(req->op.mod.message->dn)) {
		return ldb_next_request(module, req);
	}

	ldb = ldb_module_get_ctx(module);

	/*
		dn is empty so check for schemaUpdateNow attribute
		"The type of modification and values specified in the LDAP modify operation do not matter." MSDN
	*/
	if (ldb_msg_find_element(req->op.mod.message, "schemaUpdateNow")) {
		return rootdse_schemaupdatenow(module, req);
	}

	if (ldb_msg_find_element(req->op.mod.message, "enableOptionalFeature")) {
		return rootdse_enableoptionalfeature(module, req);
	}

	return LDB_ERR_OPERATIONS_ERROR;
}

_PUBLIC_ const struct ldb_module_ops ldb_rootdse_module_ops = {
	.name		= "rootdse",
	.init_context   = rootdse_init,
	.search         = rootdse_search,
	.request	= rootdse_request,
	.modify         = rootdse_modify
};