source: trunk/server/source4/nbt_server/wins/winsdb.c

/* 
   Unix SMB/CIFS implementation.

   WINS database routines

   Copyright (C) Andrew Tridgell        2005
   Copyright (C) Stefan Metzmacher      2005
      
   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 "nbt_server/nbt_server.h"
#include "nbt_server/wins/winsdb.h"
#include <ldb.h>
#include <ldb_errors.h>
#include "librpc/gen_ndr/ndr_nbt.h"
#include "system/time.h"
#include "ldb_wrap.h"
#include "system/network.h"
#include "lib/socket/netif.h"
#include "param/param.h"

uint64_t winsdb_get_maxVersion(struct winsdb_handle *h)
{
        int ret;
        struct ldb_context *ldb = h->ldb;
        struct ldb_dn *dn;
        struct ldb_result *res = NULL;
        TALLOC_CTX *tmp_ctx = talloc_new(ldb);
        uint64_t maxVersion = 0;

        dn = ldb_dn_new(tmp_ctx, ldb, "CN=VERSION");
        if (!dn) goto failed;

        /* find the record in the WINS database */
        ret = ldb_search(ldb, tmp_ctx, &res, dn, LDB_SCOPE_BASE, NULL, NULL);
        if (ret != LDB_SUCCESS) goto failed;
        if (res->count > 1) goto failed;

        if (res->count == 1) {
                maxVersion = ldb_msg_find_attr_as_uint64(res->msgs[0], "maxVersion", 0);
        }

failed:
        talloc_free(tmp_ctx);
        return maxVersion;
}

/*
 if newVersion == 0 return the old maxVersion + 1 and save it
 if newVersion > 0 return MAX(oldMaxVersion, newMaxVersion) and save it
*/
uint64_t winsdb_set_maxVersion(struct winsdb_handle *h, uint64_t newMaxVersion)
{
        int trans;
        int ret;
        struct ldb_dn *dn;
        struct ldb_result *res = NULL;
        struct ldb_message *msg = NULL;
        struct ldb_context *wins_db = h->ldb;
        TALLOC_CTX *tmp_ctx = talloc_new(wins_db);
        uint64_t oldMaxVersion = 0;

        trans = ldb_transaction_start(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        dn = ldb_dn_new(tmp_ctx, wins_db, "CN=VERSION");
        if (!dn) goto failed;

        /* find the record in the WINS database */
        ret = ldb_search(wins_db, tmp_ctx, &res, dn, LDB_SCOPE_BASE, NULL, NULL);
        if (ret != LDB_SUCCESS) goto failed;
        if (res->count > 1) goto failed;

        if (res->count == 1) {
                oldMaxVersion = ldb_msg_find_attr_as_uint64(res->msgs[0], "maxVersion", 0);
        }

        if (newMaxVersion == 0) {
                newMaxVersion = oldMaxVersion + 1;
        } else {
                newMaxVersion = MAX(oldMaxVersion, newMaxVersion);
        }

        msg = ldb_msg_new(tmp_ctx);
        if (!msg) goto failed;
        msg->dn = dn;


        ret = ldb_msg_add_empty(msg, "objectClass", LDB_FLAG_MOD_REPLACE, NULL);
        if (ret != LDB_SUCCESS) goto failed;
        ret = ldb_msg_add_string(msg, "objectClass", "winsMaxVersion");
        if (ret != LDB_SUCCESS) goto failed;
        ret = ldb_msg_add_empty(msg, "maxVersion", LDB_FLAG_MOD_REPLACE, NULL);
        if (ret != LDB_SUCCESS) goto failed;
        ret = ldb_msg_add_fmt(msg, "maxVersion", "%llu", (long long)newMaxVersion);
        if (ret != LDB_SUCCESS) goto failed;

        ret = ldb_modify(wins_db, msg);
        if (ret != LDB_SUCCESS) ret = ldb_add(wins_db, msg);
        if (ret != LDB_SUCCESS) goto failed;

        trans = ldb_transaction_commit(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        talloc_free(tmp_ctx);
        return newMaxVersion;

failed:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(wins_db);
        talloc_free(tmp_ctx);
        return 0;
}

uint64_t winsdb_get_seqnumber(struct winsdb_handle *h)
{
        int ret;
        struct ldb_context *ldb = h->ldb;
        struct ldb_dn *dn;
        struct ldb_result *res = NULL;
        TALLOC_CTX *tmp_ctx = talloc_new(ldb);
        uint64_t seqnumber = 0;

        dn = ldb_dn_new(tmp_ctx, ldb, "@BASEINFO");
        if (!dn) goto failed;

        /* find the record in the WINS database */
        ret = ldb_search(ldb, tmp_ctx, &res, dn, LDB_SCOPE_BASE, NULL, NULL);
        if (ret != LDB_SUCCESS) goto failed;
        if (res->count > 1) goto failed;

        if (res->count == 1) {
                seqnumber = ldb_msg_find_attr_as_uint64(res->msgs[0], "sequenceNumber", 0);
        }

failed:
        talloc_free(tmp_ctx);
        return seqnumber;
}

/*
  return a DN for a nbt_name
*/
static struct ldb_dn *winsdb_dn(TALLOC_CTX *mem_ctx, struct ldb_context *ldb,
                                const struct nbt_name *name)
{
        struct ldb_dn *dn;

        dn = ldb_dn_new_fmt(mem_ctx, ldb, "type=0x%02X", name->type);
        if (ldb_dn_is_valid(dn) && name->name && *name->name) {
                ldb_dn_add_child_fmt(dn, "name=%s", name->name);
        }
        if (ldb_dn_is_valid(dn) && name->scope && *name->scope) {
                ldb_dn_add_child_fmt(dn, "scope=%s", name->scope);
        }
        return dn;
}

static NTSTATUS winsdb_nbt_name(TALLOC_CTX *mem_ctx, struct ldb_dn *dn, struct nbt_name **_name)
{
        NTSTATUS status;
        struct nbt_name *name;
        unsigned int comp_num;
        uint32_t cur = 0;

        name = talloc(mem_ctx, struct nbt_name);
        if (!name) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        comp_num = ldb_dn_get_comp_num(dn);

        if (comp_num > 3) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        if (comp_num > cur && strcasecmp("scope", ldb_dn_get_component_name(dn, cur)) == 0) {
                name->scope     = (const char *)talloc_strdup(name, (char *)ldb_dn_get_component_val(dn, cur)->data);
                cur++;
        } else {
                name->scope     = NULL;
        }

        if (comp_num > cur && strcasecmp("name", ldb_dn_get_component_name(dn, cur)) == 0) {
                name->name      = (const char *)talloc_strdup(name, (char *)ldb_dn_get_component_val(dn, cur)->data);
                cur++;
        } else {
                name->name      = talloc_strdup(name, "");
                if (!name->name) {
                        status = NT_STATUS_NO_MEMORY;
                        goto failed;
                }
        }

        if (comp_num > cur && strcasecmp("type", ldb_dn_get_component_name(dn, cur)) == 0) {
                name->type      = strtoul((char *)ldb_dn_get_component_val(dn, cur)->data, NULL, 0);
                cur++;
        } else {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        *_name = name;
        return NT_STATUS_OK;
failed:
        talloc_free(name);
        return status;
}

/*
 decode the winsdb_addr("address") attribute:
 "172.31.1.1" or 
 "172.31.1.1;winsOwner:172.31.9.202;expireTime:20050923032330.0Z;"
 are valid records
*/
static NTSTATUS winsdb_addr_decode(struct winsdb_handle *h, struct winsdb_record *rec, struct ldb_val *val,
                                   TALLOC_CTX *mem_ctx, struct winsdb_addr **_addr)
{
        NTSTATUS status;
        struct winsdb_addr *addr;
        const char *address;
        const char *wins_owner;
        const char *expire_time;
        char *p;

        addr = talloc(mem_ctx, struct winsdb_addr);
        if (!addr) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        address = (char *)val->data;

        p = strchr(address, ';');
        if (!p) {
                /* support old entries, with only the address */
                addr->address           = (const char *)talloc_steal(addr, val->data);
                addr->wins_owner        = talloc_reference(addr, rec->wins_owner);
                if (!addr->wins_owner) {
                        status = NT_STATUS_NO_MEMORY;
                        goto failed;
                }
                addr->expire_time       = rec->expire_time;
                *_addr = addr;
                return NT_STATUS_OK;
        }

        *p = '\0'; p++;
        addr->address = talloc_strdup(addr, address);
        if (!addr->address) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        if (strncmp("winsOwner:", p, 10) != 0) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }
        wins_owner = p + 10;
        p = strchr(wins_owner, ';');
        if (!p) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        *p = '\0';p++;
        if (strcmp(wins_owner, "0.0.0.0") == 0) {
                wins_owner = h->local_owner;
        }
        addr->wins_owner = talloc_strdup(addr, wins_owner);
        if (!addr->wins_owner) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        if (strncmp("expireTime:", p, 11) != 0) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        expire_time = p + 11;
        p = strchr(expire_time, ';');
        if (!p) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        *p = '\0';p++;
        addr->expire_time = ldb_string_to_time(expire_time);

        *_addr = addr;
        return NT_STATUS_OK;
failed:
        talloc_free(addr);
        return status;
}

/*
 encode the winsdb_addr("address") attribute like this:
 non-static record:
 "172.31.1.1;winsOwner:172.31.9.202;expireTime:20050923032330.0Z;"
 static record:
 "172.31.1.1"
*/
static int ldb_msg_add_winsdb_addr(struct ldb_message *msg, struct winsdb_record *rec,
                                   const char *attr_name, struct winsdb_addr *addr)
{
        const char *str;

        if (rec->is_static) {
                str = talloc_strdup(msg, addr->address);
                if (!str) return LDB_ERR_OPERATIONS_ERROR;
        } else {
                char *expire_time;
                expire_time = ldb_timestring(msg, addr->expire_time);
                if (!expire_time) return LDB_ERR_OPERATIONS_ERROR;
                str = talloc_asprintf(msg, "%s;winsOwner:%s;expireTime:%s;",
                                      addr->address, addr->wins_owner,
                                      expire_time);
                talloc_free(expire_time);
                if (!str) return LDB_ERR_OPERATIONS_ERROR;
        }

        return ldb_msg_add_string(msg, attr_name, str);
}

struct winsdb_addr **winsdb_addr_list_make(TALLOC_CTX *mem_ctx)
{
        struct winsdb_addr **addresses;

        addresses = talloc_array(mem_ctx, struct winsdb_addr *, 1);
        if (!addresses) return NULL;

        addresses[0] = NULL;

        return addresses;
}

static int winsdb_addr_sort_list (struct winsdb_addr **p1, struct winsdb_addr **p2, void *opaque)
{
        struct winsdb_addr *a1 = talloc_get_type(*p1, struct winsdb_addr);
        struct winsdb_addr *a2 = talloc_get_type(*p2, struct winsdb_addr);
        struct winsdb_handle *h= talloc_get_type(opaque, struct winsdb_handle);
        bool a1_owned = false;
        bool a2_owned = false;

        /*
         * first the owned addresses with the newest to the oldest address
         * then the replica addresses with the newest to the oldest address
         */
        if (a2->expire_time != a1->expire_time) {
                return a2->expire_time - a1->expire_time;
        }

        if (strcmp(a2->wins_owner, h->local_owner) == 0) {
                a2_owned = true;
        }

        if (strcmp(a1->wins_owner, h->local_owner) == 0) {
                a1_owned = true;
        }

        return a2_owned - a1_owned;
}

struct winsdb_addr **winsdb_addr_list_add(struct winsdb_handle *h, const struct winsdb_record *rec,
                                          struct winsdb_addr **addresses, const char *address,
                                          const char *wins_owner, time_t expire_time,
                                          bool is_name_registration)
{
        struct winsdb_addr *old_addr = NULL;
        size_t len = 0;
        size_t i;
        bool found_old_replica = false;

        /*
         * count the addresses and maybe
         * find an old entry for the new address
         */
        for (i=0; addresses[i]; i++) {
                if (old_addr) continue;
                if (strcmp(addresses[i]->address, address) == 0) {
                        old_addr = addresses[i];
                }
        }
        len = i;

        /*
         * the address is already there
         * and we can replace it
         */
        if (old_addr) {
                goto remove_old_addr;
        }

        /*
         * if we don't have 25 addresses already,
         * we can just add the new address
         */
        if (len < 25) {
                goto add_new_addr;
        }

        /*
         * if we haven't found the address,
         * and we have already have 25 addresses
         * if so then we need to do the following:
         * - if it isn't a name registration, then just ignore the new address
         * - if it is a name registration, then first search for 
         *   the oldest replica and if there's no replica address
         *   search the oldest owned address
         */
        if (!is_name_registration) {
                return addresses;
        }

        /*
         * find the oldest replica address, if there's no replica
         * record at all, find the oldest owned address
         */
        for (i=0; addresses[i]; i++) {
                bool cur_is_replica = false;
                /* find out if the current address is a replica */
                if (strcmp(addresses[i]->wins_owner, h->local_owner) != 0) {
                        cur_is_replica = true;
                }

                /*
                 * if we already found a replica address and the current address
                 * is not a replica, then skip it
                 */
                if (found_old_replica && !cur_is_replica) continue;

                /*
                 * if we found the first replica address, reset the address
                 * that would be replaced
                 */
                if (!found_old_replica && cur_is_replica) {
                        found_old_replica = true;
                        old_addr = addresses[i];
                        continue;
                }

                /*
                 * if the first address isn't a replica, just start with 
                 * the first one
                 */
                if (!old_addr) {
                        old_addr = addresses[i];
                        continue;
                }

                /*
                 * see if we find an older address
                 */
                if (addresses[i]->expire_time < old_addr->expire_time) {
                        old_addr = addresses[i];
                        continue;
                }
        }

remove_old_addr:
        winsdb_addr_list_remove(addresses, old_addr->address);
        len --;

add_new_addr:
        addresses = talloc_realloc(addresses, addresses, struct winsdb_addr *, len + 2);
        if (!addresses) return NULL;

        addresses[len] = talloc(addresses, struct winsdb_addr);
        if (!addresses[len]) {
                talloc_free(addresses);
                return NULL;
        }

        addresses[len]->address = talloc_strdup(addresses[len], address);
        if (!addresses[len]->address) {
                talloc_free(addresses);
                return NULL;
        }

        addresses[len]->wins_owner = talloc_strdup(addresses[len], wins_owner);
        if (!addresses[len]->wins_owner) {
                talloc_free(addresses);
                return NULL;
        }

        addresses[len]->expire_time = expire_time;

        addresses[len+1] = NULL;

        LDB_TYPESAFE_QSORT(addresses, len+1, h, winsdb_addr_sort_list);

        return addresses;
}

void winsdb_addr_list_remove(struct winsdb_addr **addresses, const char *address)
{
        size_t i;

        for (i=0; addresses[i]; i++) {
                if (strcmp(addresses[i]->address, address) == 0) {
                        break;
                }
        }

        for (; addresses[i]; i++) {
                addresses[i] = addresses[i+1];
        }

        return;
}

struct winsdb_addr *winsdb_addr_list_check(struct winsdb_addr **addresses, const char *address)
{
        size_t i;

        for (i=0; addresses[i]; i++) {
                if (strcmp(addresses[i]->address, address) == 0) {
                        return addresses[i];
                }
        }

        return NULL;
}

size_t winsdb_addr_list_length(struct winsdb_addr **addresses)
{
        size_t i;
        for (i=0; addresses[i]; i++);
        return i;
}

const char **winsdb_addr_string_list(TALLOC_CTX *mem_ctx, struct winsdb_addr **addresses)
{
        size_t len = winsdb_addr_list_length(addresses);
        const char **str_list=NULL;
        size_t i;

        for (i=0; i < len; i++) {
                str_list = str_list_add(str_list, addresses[i]->address);
                if (!str_list[i]) {
                        return NULL;
                }
        }
        talloc_steal(mem_ctx, str_list);
        return str_list;
}

/*
  load a WINS entry from the database
*/
NTSTATUS winsdb_lookup(struct winsdb_handle *h, 
                       const struct nbt_name *name,
                       TALLOC_CTX *mem_ctx,
                       struct winsdb_record **_rec)
{
        NTSTATUS status;
        struct ldb_result *res = NULL;
        int ret;
        struct winsdb_record *rec;
        struct ldb_context *wins_db = h->ldb;
        TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
        time_t now = time(NULL);

        /* find the record in the WINS database */
        ret = ldb_search(wins_db, tmp_ctx, &res,
                         winsdb_dn(tmp_ctx, wins_db, name),
                         LDB_SCOPE_BASE, NULL, NULL);

        if (ret != LDB_SUCCESS || res->count > 1) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        } else if (res->count== 0) {
                status = NT_STATUS_OBJECT_NAME_NOT_FOUND;
                goto failed;
        }

        status = winsdb_record(h, res->msgs[0], tmp_ctx, now, &rec);
        if (!NT_STATUS_IS_OK(status)) goto failed;

        talloc_steal(mem_ctx, rec);
        talloc_free(tmp_ctx);
        *_rec = rec;
        return NT_STATUS_OK;

failed:
        talloc_free(tmp_ctx);
        return status;
}

NTSTATUS winsdb_record(struct winsdb_handle *h, struct ldb_message *msg, TALLOC_CTX *mem_ctx, time_t now, struct winsdb_record **_rec)
{
        NTSTATUS status;
        struct winsdb_record *rec;
        struct ldb_message_element *el;
        struct nbt_name *name;
        uint32_t i, j, num_values;

        rec = talloc(mem_ctx, struct winsdb_record);
        if (rec == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        status = winsdb_nbt_name(rec, msg->dn, &name);
        if (!NT_STATUS_IS_OK(status)) goto failed;

        if (strlen(name->name) > 15) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }
        if (name->scope && strlen(name->scope) > 238) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        /* parse it into a more convenient winsdb_record structure */
        rec->name               = name;
        rec->type               = ldb_msg_find_attr_as_int(msg, "recordType", WREPL_TYPE_UNIQUE);
        rec->state              = ldb_msg_find_attr_as_int(msg, "recordState", WREPL_STATE_RELEASED);
        rec->node               = ldb_msg_find_attr_as_int(msg, "nodeType", WREPL_NODE_B);
        rec->is_static          = ldb_msg_find_attr_as_int(msg, "isStatic", 0);
        rec->expire_time        = ldb_string_to_time(ldb_msg_find_attr_as_string(msg, "expireTime", NULL));
        rec->version            = ldb_msg_find_attr_as_uint64(msg, "versionID", 0);
        rec->wins_owner         = ldb_msg_find_attr_as_string(msg, "winsOwner", NULL);
        rec->registered_by      = ldb_msg_find_attr_as_string(msg, "registeredBy", NULL);
        talloc_steal(rec, rec->wins_owner);
        talloc_steal(rec, rec->registered_by);

        if (!rec->wins_owner || strcmp(rec->wins_owner, "0.0.0.0") == 0) {
                rec->wins_owner = h->local_owner;
        }

        el = ldb_msg_find_element(msg, "address");
        if (el) {
                num_values = el->num_values;
        } else {
                num_values = 0;
        }

        if (rec->type == WREPL_TYPE_UNIQUE || rec->type == WREPL_TYPE_GROUP) {
                if (num_values != 1) {
                        status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                        goto failed;
                }
        }
        if (rec->state == WREPL_STATE_ACTIVE) {
                if (num_values < 1) {
                        status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                        goto failed;
                }
        }
        if (num_values > 25) {
                status = NT_STATUS_INTERNAL_DB_CORRUPTION;
                goto failed;
        }

        rec->addresses     = talloc_array(rec, struct winsdb_addr *, num_values+1);
        if (rec->addresses == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        for (i=0,j=0;i<num_values;i++) {
                bool we_are_owner = false;

                status = winsdb_addr_decode(h, rec, &el->values[i], rec->addresses, &rec->addresses[j]);
                if (!NT_STATUS_IS_OK(status)) goto failed;

                if (strcmp(rec->addresses[j]->wins_owner, h->local_owner) == 0) {
                        we_are_owner = true;
                }

                /*
                 * the record isn't static and is active
                 * then don't add the address if it's expired,
                 * but only if we're the owner of the address
                 *
                 * This is important for SGROUP records,
                 * because each server thinks he's the owner of the
                 * record and the record isn't replicated on a
                 * name_refresh. So addresses owned by another owner
                 * could expire, but we still need to return them
                 * (as windows does).
                 */
                if (!rec->is_static &&
                    rec->addresses[j]->expire_time <= now &&
                    rec->state == WREPL_STATE_ACTIVE &&
                    we_are_owner) {
                        DEBUG(5,("WINS: expiring name addr %s of %s (expired at %s)\n", 
                                 rec->addresses[j]->address, nbt_name_string(rec->addresses[j], rec->name),
                                 timestring(rec->addresses[j], rec->addresses[j]->expire_time)));
                        talloc_free(rec->addresses[j]);
                        rec->addresses[j] = NULL;
                        continue;
                }
                j++;
        }
        rec->addresses[j] = NULL;
        num_values = j;

        if (rec->is_static && rec->state == WREPL_STATE_ACTIVE) {
                rec->expire_time = get_time_t_max();
                for (i=0;rec->addresses[i];i++) {
                        rec->addresses[i]->expire_time = rec->expire_time;
                }
        }

        if (rec->state == WREPL_STATE_ACTIVE) {
                if (num_values < 1) {
                        DEBUG(5,("WINS: expiring name %s (because it has no active addresses)\n", 
                                 nbt_name_string(mem_ctx, rec->name)));
                        rec->state = WREPL_STATE_RELEASED;
                }
        }

        *_rec = rec;
        return NT_STATUS_OK;
failed:
        if (NT_STATUS_EQUAL(NT_STATUS_INTERNAL_DB_CORRUPTION, status)) {
                DEBUG(1,("winsdb_record: corrupted record: %s\n", ldb_dn_get_linearized(msg->dn)));
        }
        talloc_free(rec);
        return status;
}

/*
  form a ldb_message from a winsdb_record
*/
static struct ldb_message *winsdb_message(struct ldb_context *ldb,
                                          struct winsdb_record *rec,
                                          TALLOC_CTX *mem_ctx)
{
        int i, ret;
        size_t addr_count;
        const char *expire_time;
        struct ldb_message *msg = ldb_msg_new(mem_ctx);
        if (msg == NULL) goto failed;

        /* make sure we don't put in corrupted records */
        addr_count = winsdb_addr_list_length(rec->addresses);
        if (rec->state == WREPL_STATE_ACTIVE && addr_count == 0) {
                rec->state = WREPL_STATE_RELEASED;
        }
        if (rec->type == WREPL_TYPE_UNIQUE && addr_count > 1) {
                rec->type = WREPL_TYPE_MHOMED;
        }

        expire_time = ldb_timestring(msg, rec->expire_time);
        if (!expire_time) {
                goto failed;
        }

        msg->dn = winsdb_dn(msg, ldb, rec->name);
        if (msg->dn == NULL) goto failed;
        ret = ldb_msg_add_fmt(msg, "type", "0x%02X", rec->name->type);
        if (rec->name->name && *rec->name->name) {
                ret |= ldb_msg_add_string(msg, "name", rec->name->name);
        }
        if (rec->name->scope && *rec->name->scope) {
                ret |= ldb_msg_add_string(msg, "scope", rec->name->scope);
        }
        ret |= ldb_msg_add_fmt(msg, "objectClass", "winsRecord");
        ret |= ldb_msg_add_fmt(msg, "recordType", "%u", rec->type);
        ret |= ldb_msg_add_fmt(msg, "recordState", "%u", rec->state);
        ret |= ldb_msg_add_fmt(msg, "nodeType", "%u", rec->node);
        ret |= ldb_msg_add_fmt(msg, "isStatic", "%u", rec->is_static);
        ret |= ldb_msg_add_empty(msg, "expireTime", 0, NULL);
        if (!(rec->is_static && rec->state == WREPL_STATE_ACTIVE)) {
                ret |= ldb_msg_add_string(msg, "expireTime", expire_time);
        }
        ret |= ldb_msg_add_fmt(msg, "versionID", "%llu", (long long)rec->version);
        ret |= ldb_msg_add_string(msg, "winsOwner", rec->wins_owner);
        ret |= ldb_msg_add_empty(msg, "address", 0, NULL);
        for (i=0;rec->addresses[i];i++) {
                ret |= ldb_msg_add_winsdb_addr(msg, rec, "address", rec->addresses[i]);
        }
        if (rec->registered_by) {
                ret |= ldb_msg_add_empty(msg, "registeredBy", 0, NULL);
                ret |= ldb_msg_add_string(msg, "registeredBy", rec->registered_by);
        }
        if (ret != LDB_SUCCESS) goto failed;
        return msg;

failed:
        talloc_free(msg);
        return NULL;
}

/*
  save a WINS record into the database
*/
uint8_t winsdb_add(struct winsdb_handle *h, struct winsdb_record *rec, uint32_t flags)
{
        struct ldb_message *msg;
        struct ldb_context *wins_db = h->ldb;
        TALLOC_CTX *tmp_ctx = talloc_new(wins_db);
        int trans = -1;
        int ret;

        trans = ldb_transaction_start(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        if (flags & WINSDB_FLAG_ALLOC_VERSION) {
                /* passing '0' means auto-allocate a new one */
                rec->version = winsdb_set_maxVersion(h, 0);
                if (rec->version == 0) goto failed;
        }
        if (flags & WINSDB_FLAG_TAKE_OWNERSHIP) {
                rec->wins_owner = h->local_owner;
        }

        msg = winsdb_message(wins_db, rec, tmp_ctx);
        if (msg == NULL) goto failed;
        ret = ldb_add(wins_db, msg);
        if (ret != LDB_SUCCESS) goto failed;

        trans = ldb_transaction_commit(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        wins_hook(h, rec, WINS_HOOK_ADD, h->hook_script);

        talloc_free(tmp_ctx);
        return NBT_RCODE_OK;

failed:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(wins_db);
        talloc_free(tmp_ctx);
        return NBT_RCODE_SVR;
}


/*
  modify a WINS record in the database
*/
uint8_t winsdb_modify(struct winsdb_handle *h, struct winsdb_record *rec, uint32_t flags)
{
        struct ldb_message *msg;
        struct ldb_context *wins_db = h->ldb;
        TALLOC_CTX *tmp_ctx = talloc_new(wins_db);
        int trans;
        int ret;
        unsigned int i;

        trans = ldb_transaction_start(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        if (flags & WINSDB_FLAG_ALLOC_VERSION) {
                /* passing '0' means auto-allocate a new one */
                rec->version = winsdb_set_maxVersion(h, 0);
                if (rec->version == 0) goto failed;
        }
        if (flags & WINSDB_FLAG_TAKE_OWNERSHIP) {
                rec->wins_owner = h->local_owner;
        }

        msg = winsdb_message(wins_db, rec, tmp_ctx);
        if (msg == NULL) goto failed;

        for (i=0;i<msg->num_elements;i++) {
                msg->elements[i].flags = LDB_FLAG_MOD_REPLACE;
        }

        ret = ldb_modify(wins_db, msg);
        if (ret != LDB_SUCCESS) goto failed;

        trans = ldb_transaction_commit(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        wins_hook(h, rec, WINS_HOOK_MODIFY, h->hook_script);

        talloc_free(tmp_ctx);
        return NBT_RCODE_OK;

failed:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(wins_db);
        talloc_free(tmp_ctx);
        return NBT_RCODE_SVR;
}


/*
  delete a WINS record from the database
*/
uint8_t winsdb_delete(struct winsdb_handle *h, struct winsdb_record *rec)
{
        struct ldb_context *wins_db = h->ldb;
        TALLOC_CTX *tmp_ctx = talloc_new(wins_db);
        struct ldb_dn *dn;
        int trans;
        int ret;

        trans = ldb_transaction_start(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        dn = winsdb_dn(tmp_ctx, wins_db, rec->name);
        if (dn == NULL) goto failed;

        ret = ldb_delete(wins_db, dn);
        if (ret != LDB_SUCCESS) goto failed;

        trans = ldb_transaction_commit(wins_db);
        if (trans != LDB_SUCCESS) goto failed;

        wins_hook(h, rec, WINS_HOOK_DELETE, h->hook_script);

        talloc_free(tmp_ctx);
        return NBT_RCODE_OK;

failed:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(wins_db);
        talloc_free(tmp_ctx);
        return NBT_RCODE_SVR;
}

static bool winsdb_check_or_add_module_list(struct tevent_context *ev_ctx, 
                                            struct loadparm_context *lp_ctx, struct winsdb_handle *h)
{
        int trans;
        int ret;
        struct ldb_dn *dn;
        struct ldb_result *res = NULL;
        struct ldb_message *msg = NULL;
        TALLOC_CTX *tmp_ctx = talloc_new(h);
        unsigned int flags = 0;

        trans = ldb_transaction_start(h->ldb);
        if (trans != LDB_SUCCESS) goto failed;

        /* check if we have a special @MODULES record already */
        dn = ldb_dn_new(tmp_ctx, h->ldb, "@MODULES");
        if (!dn) goto failed;

        /* find the record in the WINS database */
        ret = ldb_search(h->ldb, tmp_ctx, &res, dn, LDB_SCOPE_BASE, NULL, NULL);
        if (ret != LDB_SUCCESS) goto failed;

        if (res->count > 0) goto skip;

        /* if there's no record, add one */
        msg = ldb_msg_new(tmp_ctx);
        if (!msg) goto failed;
        msg->dn = dn;

        ret = ldb_msg_add_string(msg, "@LIST", "wins_ldb");
        if (ret != LDB_SUCCESS) goto failed;

        ret = ldb_add(h->ldb, msg);
        if (ret != LDB_SUCCESS) goto failed;

        trans = ldb_transaction_commit(h->ldb);
        if (trans != LDB_SUCCESS) goto failed;

        /* close and reopen the database, with the modules */
        trans = LDB_ERR_OTHER;
        talloc_free(h->ldb);
        h->ldb = NULL;

        if (lpcfg_parm_bool(lp_ctx, NULL,"winsdb", "nosync", false)) {
                flags |= LDB_FLG_NOSYNC;
        }

        h->ldb = ldb_wrap_connect(h, ev_ctx, lp_ctx, lock_path(h, lp_ctx, lpcfg_wins_url(lp_ctx)),
                                  NULL, NULL, flags);
        if (!h->ldb) goto failed;

        talloc_free(tmp_ctx);
        return true;

skip:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(h->ldb);
        talloc_free(tmp_ctx);
        return true;

failed:
        if (trans == LDB_SUCCESS) ldb_transaction_cancel(h->ldb);
        talloc_free(tmp_ctx);
        return false;
}

struct winsdb_handle *winsdb_connect(TALLOC_CTX *mem_ctx, 
                                     struct tevent_context *ev_ctx,
                                     struct loadparm_context *lp_ctx,
                                     const char *owner,
                                     enum winsdb_handle_caller caller)
{
        struct winsdb_handle *h = NULL;
        unsigned int flags = 0;
        bool ret;
        int ldb_err;

        h = talloc_zero(mem_ctx, struct winsdb_handle);
        if (!h) return NULL;

        if (lpcfg_parm_bool(lp_ctx, NULL,"winsdb", "nosync", false)) {
                flags |= LDB_FLG_NOSYNC;
        }

        h->ldb = ldb_wrap_connect(h, ev_ctx, lp_ctx, lock_path(h, lp_ctx, lpcfg_wins_url(lp_ctx)),
                                  NULL, NULL, flags);
        if (!h->ldb) goto failed;

        h->caller = caller;
        h->hook_script = lpcfg_wins_hook(lp_ctx);

        h->local_owner = talloc_strdup(h, owner);
        if (!h->local_owner) goto failed;

        /* make sure the module list is available and used */
        ret = winsdb_check_or_add_module_list(ev_ctx, lp_ctx, h);
        if (!ret) goto failed;

        ldb_err = ldb_set_opaque(h->ldb, "winsdb_handle", h);
        if (ldb_err != LDB_SUCCESS) goto failed;

        return h;
failed:
        talloc_free(h);
        return NULL;
}