dlz/drivers/dlz_ldap_driver.c

/*
 * Copyright (C) 2002 Stichting NLnet, Netherlands, stichting@nlnet.nl.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all
 * copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND STICHTING NLNET
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * STICHTING NLNET BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE
 * USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * The development of Dynamically Loadable Zones (DLZ) for BIND 9 was
 * conceived and contributed by Rob Butler.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all
 * copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ROB BUTLER
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * ROB BUTLER BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE
 * USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Copyright (C) 1999-2001, 2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

#ifdef DLZ_LDAP

#include <config.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <dns/log.h>
#include <dns/sdlz.h>
#include <dns/result.h>

#include <isc/mem.h>
#include <isc/platform.h>
#include <isc/print.h>
#include <isc/result.h>
#include <isc/string.h>
#include <isc/util.h>

#include <named/globals.h>

#include <dlz/sdlz_helper.h>
#include <dlz/dlz_ldap_driver.h>

/*
 * Need older API functions from ldap.h.
 */
#define LDAP_DEPRECATED 1

#include <ldap.h>

#define SIMPLE "simple"
#define KRB41 "krb41"
#define KRB42 "krb42"
#define V2 "v2"
#define V3 "v3"

static dns_sdlzimplementation_t *dlz_ldap = NULL;

#define dbc_search_limit 30
#define ALLNODES 1
#define ALLOWXFR 2
#define AUTHORITY 3
#define FINDZONE 4
#define LOOKUP 5

/*%
 * Structure to hold everthing needed by this "instance" of the LDAP
 * driver remember, the driver code is only loaded once, but may have
 * many separate instances.
 */

typedef struct {
#ifdef ISC_PLATFORM_USETHREADS
    db_list_t    *db; /*%< handle to a list of DB */
#else
    dbinstance_t *db; /*%< handle to db */
#endif
    int method; /*%< security authentication method */
    char *user; /*%< who is authenticating */
    char *cred; /*%< password for simple authentication method */
    int protocol;   /*%< LDAP communication protocol version */
    char *hosts;    /*%< LDAP server hosts */
} ldap_instance_t;

/* forward references */

static isc_result_t
dlz_ldap_findzone(void *driverarg, void *dbdata, const char *name,
          dns_clientinfomethods_t *methods,
          dns_clientinfo_t *clientinfo);

static void
dlz_ldap_destroy(void *driverarg, void *dbdata);

/*
 * Private methods
 */

/*% checks that the LDAP URL parameters make sense */
static isc_result_t
dlz_ldap_checkURL(char *URL, int attrCnt, const char *msg) {
    isc_result_t result = ISC_R_SUCCESS;
    int ldap_result;
    LDAPURLDesc *ldap_url = NULL;

    if (!ldap_is_ldap_url(URL)) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s query is not a valid LDAP URL", msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    ldap_result = ldap_url_parse(URL, &ldap_url);
    if (ldap_result != LDAP_SUCCESS || ldap_url == NULL) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "parsing %s query failed", msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    if (ldap_count_values(ldap_url->lud_attrs) < attrCnt) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s query must specify at least "
                  "%d attributes to return",
                  msg, attrCnt);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    if (ldap_url->lud_host != NULL) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s query must not specify a host", msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    if (ldap_url->lud_port != 389) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s query must not specify a port", msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    if (ldap_url->lud_dn == NULL || strlen (ldap_url->lud_dn) < 1) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s query must specify a search base", msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    if (ldap_url->lud_exts != NULL || ldap_url->lud_crit_exts != 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "%s uses extensions. "
                  "The driver does not support LDAP extensions.",
                  msg);
        result = ISC_R_FAILURE;
        goto cleanup;
    }

 cleanup:
    if (ldap_url != NULL)
        ldap_free_urldesc(ldap_url);

    return (result);
}

/*% Connects / reconnects to LDAP server */
static isc_result_t
dlz_ldap_connect(ldap_instance_t *dbi, dbinstance_t *dbc) {
    isc_result_t result;
    int ldap_result;

    /* if we have a connection, get ride of it. */
    if (dbc->dbconn != NULL) {
        ldap_unbind_s((LDAP *) dbc->dbconn);
        dbc->dbconn = NULL;
    }

    /* now connect / reconnect. */

    /* initialize. */
    dbc->dbconn = ldap_init(dbi->hosts, LDAP_PORT);
    if (dbc->dbconn == NULL)
        return (ISC_R_NOMEMORY);

    /* set protocol version. */
    ldap_result = ldap_set_option((LDAP *) dbc->dbconn,
                      LDAP_OPT_PROTOCOL_VERSION,
                      &(dbi->protocol));
    if (ldap_result != LDAP_SUCCESS) {
        result = ISC_R_NOPERM;
        goto cleanup;
    }

    /* "bind" to server.  i.e. send username / pass */
    ldap_result = ldap_bind_s((LDAP *) dbc->dbconn, dbi->user,
                  dbi->cred, dbi->method);
    if (ldap_result != LDAP_SUCCESS) {
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    return (ISC_R_SUCCESS);

 cleanup:

    /* cleanup if failure. */
    if (dbc->dbconn != NULL) {
        ldap_unbind_s((LDAP *) dbc->dbconn);
        dbc->dbconn = NULL;
    }

    return (result);
}

#ifdef ISC_PLATFORM_USETHREADS


/*%
 * Properly cleans up a list of database instances.
 * This function is only used when the driver is compiled for
 * multithreaded operation.
 */
static void
ldap_destroy_dblist(db_list_t *dblist) {
    dbinstance_t *ndbi = NULL;
    dbinstance_t *dbi = NULL;

    /* get the first DBI in the list */
    ndbi = ISC_LIST_HEAD(*dblist);

    /* loop through the list */
    while (ndbi != NULL) {
        dbi = ndbi;
        /* get the next DBI in the list */
        ndbi = ISC_LIST_NEXT(dbi, link);
        /* release DB connection */
        if (dbi->dbconn != NULL)
            ldap_unbind_s((LDAP *) dbi->dbconn);
        /* release all memory that comprised a DBI */
        destroy_sqldbinstance(dbi);
    }
    /* release memory for the list structure */
    isc_mem_put(ns_g_mctx, dblist, sizeof(db_list_t));
}

/*%
 * Loops through the list of DB instances, attempting to lock
 * on the mutex.  If successful, the DBI is reserved for use
 * and the thread can perform queries against the database.
 * If the lock fails, the next one in the list is tried.
 * looping continues until a lock is obtained, or until
 * the list has been searched dbc_search_limit times.
 * This function is only used when the driver is compiled for
 * multithreaded operation.
 */
static dbinstance_t *
ldap_find_avail_conn(db_list_t *dblist) {
    dbinstance_t *dbi = NULL;
    dbinstance_t *head;
    int count = 0;

    /* get top of list */
    head = dbi = ISC_LIST_HEAD(*dblist);

    /* loop through list */
    while (count < dbc_search_limit) {
        /* try to lock on the mutex */
        if (isc_mutex_trylock(&dbi->instance_lock) == ISC_R_SUCCESS)
            return (dbi); /* success, return the DBI for use. */

        /* not successful, keep trying */
        dbi = ISC_LIST_NEXT(dbi, link);

        /* check to see if we have gone to the top of the list. */
        if (dbi == NULL) {
            count++;
            dbi = head;
        }
    }
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_INFO,
              "LDAP driver unable to find available connection "
              "after searching %d times",
              count);
    return (NULL);
}
#endif /* ISC_PLATFORM_USETHREADS */

static isc_result_t
ldap_process_results(LDAP *dbc, LDAPMessage *msg, char ** attrs,
             void *ptr, isc_boolean_t allnodes)
{
    isc_result_t result = ISC_R_SUCCESS;
    int i = 0;
    int j;
    int len;
    char *attribute = NULL;
    LDAPMessage *entry;
    char *endp = NULL;
    char *host = NULL;
    char *type = NULL;
    char *data = NULL;
    char **vals = NULL;
    int ttl;

    /* make sure there are at least some attributes to process. */
    REQUIRE(attrs != NULL || attrs[0] != NULL);

    /* get the first entry to process */
    entry = ldap_first_entry(dbc, msg);
    if (entry == NULL) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_INFO,
                  "LDAP no entries to process.");
        return (ISC_R_FAILURE);
    }

    /* loop through all entries returned */
    while (entry != NULL) {
        /* reset for this loop */
        ttl = 0;
        len = 0;
        i = 0;
        attribute = attrs[i];

        /* determine how much space we need for data string */
        for (j = 0; attrs[j] != NULL; j++) {
            /* get the list of values for this attribute. */
            vals = ldap_get_values(dbc, entry, attrs[j]);
            /* skip empty attributes. */
            if (vals == NULL || ldap_count_values(vals) < 1)
                continue;
            /*
             * we only use the first value.  this driver
             * does not support multi-valued attributes.
             */
            len = len + strlen(vals[0]) + 1;
            /* free vals for next loop */
            ldap_value_free(vals);
        } /* end for (j = 0; attrs[j] != NULL, j++) loop */

        /* allocate memory for data string */
        data = isc_mem_allocate(ns_g_mctx, len + 1);
        if (data == NULL) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver unable to allocate memory "
                      "while processing results");
            result = ISC_R_FAILURE;
            goto cleanup;
        }

        /*
         * Make sure data is null termed at the beginning so
         * we can check if any data was stored to it later.
         */
        data[0] = '\0';

        /* reset j to re-use below */
        j = 0;

        /* loop through the attributes in the order specified. */
        while (attribute != NULL) {
            /* get the list of values for this attribute. */
            vals = ldap_get_values(dbc, entry, attribute);

            /* skip empty attributes. */
            if (vals == NULL || vals[0] == NULL) {
                /* increment attibute pointer */
                attribute = attrs[++i];
                /* start loop over */
                continue;
            }

            /*
             * j initially = 0.  Increment j each time we
             * set a field that way next loop will set
             * next field.
             */
            switch(j) {
            case 0:
                j++;
                /*
                 * convert text to int, make sure it
                 * worked right
                 */
                ttl = strtol(vals[0], &endp, 10);
                if (*endp != '\0' || ttl < 0) {
                    isc_log_write(dns_lctx,
                              DNS_LOGCATEGORY_DATABASE,
                              DNS_LOGMODULE_DLZ,
                              ISC_LOG_ERROR,
                              "LDAP driver ttl must "
                              "be a postive number");
                    goto cleanup;
                }
                break;
            case 1:
                j++;
                type = isc_mem_strdup(ns_g_mctx, vals[0]);
                break;
            case 2:
                j++;
                if (allnodes)
                    host = isc_mem_strdup(ns_g_mctx,
                                  vals[0]);
                else
                    strcpy(data, vals[0]);
                break;
            case 3:
                j++;
                if (allnodes)
                    strcpy(data, vals[0]);
                else {
                    strcat(data, " ");
                    strcat(data, vals[0]);
                }
                break;
            default:
                strcat(data, " ");
                strcat(data, vals[0]);
                break;
            } /* end switch(j) */

            /* free values */
            ldap_value_free(vals);
            vals = NULL;

            /* increment attibute pointer */
            attribute = attrs[++i];
        }   /* end while (attribute != NULL) */

        if (type == NULL) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver unable "
                      "to retrieve DNS type");
            result = ISC_R_FAILURE;
            goto cleanup;
        }

        if (strlen(data) < 1) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver unable "
                      "to retrieve DNS data");
            result = ISC_R_FAILURE;
            goto cleanup;
        }

        if (allnodes && host != NULL) {
            if (strcasecmp(host, "~") == 0)
                result = dns_sdlz_putnamedrr(
                        (dns_sdlzallnodes_t *) ptr,
                        "*", type, ttl, data);
            else
                result = dns_sdlz_putnamedrr(
                        (dns_sdlzallnodes_t *) ptr,
                        host, type, ttl, data);
            if (result != ISC_R_SUCCESS)
                isc_log_write(dns_lctx,
                    DNS_LOGCATEGORY_DATABASE,
                    DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                    "dlz-ldap: putnamedrr failed "
                    "for \"%s %s %u %s\", %s",
                    host, type, ttl, data,
                    isc_result_totext(result));
        } else {
            result = dns_sdlz_putrr((dns_sdlzlookup_t *) ptr,
                        type, ttl, data);
            if (result != ISC_R_SUCCESS)
                isc_log_write(dns_lctx,
                    DNS_LOGCATEGORY_DATABASE,
                    DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                    "dlz-ldap: putrr failed "
                    "for \"%s %u %s\", %s",
                    type, ttl, data,
                    isc_result_totext(result));
        }

        if (result != ISC_R_SUCCESS) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver failed "
                      "while sending data to BIND.");
            goto cleanup;
        }

        /* free memory for type, data and host for next loop */
        isc_mem_free(ns_g_mctx, type);
        isc_mem_free(ns_g_mctx, data);
        if (host != NULL)
            isc_mem_free(ns_g_mctx, host);

        /* get the next entry to process */
        entry = ldap_next_entry(dbc, entry);
    } /* end while (entry != NULL) */

 cleanup:
    /* de-allocate memory */
    if (vals != NULL)
        ldap_value_free(vals);
    if (host != NULL)
        isc_mem_free(ns_g_mctx, host);
    if (type != NULL)
        isc_mem_free(ns_g_mctx, type);
    if (data != NULL)
        isc_mem_free(ns_g_mctx, data);

    return (result);
}

/*%
 * This function is the real core of the driver.   Zone, record
 * and client strings are passed in (or NULL is passed if the
 * string is not available).  The type of query we want to run
 * is indicated by the query flag, and the dbdata object is passed
 * passed in to.  dbdata really holds either:
 *      1) a list of database instances (in multithreaded mode) OR
 *      2) a single database instance (in single threaded mode)
 * The function will construct the query and obtain an available
 * database instance (DBI).  It will then run the query and hopefully
 * obtain a result set.
 */
static isc_result_t
ldap_get_results(const char *zone, const char *record,
         const char *client, unsigned int query,
         void *dbdata, void *ptr)
{
    isc_result_t result;
    dbinstance_t *dbi = NULL;
    char *querystring = NULL;
    LDAPURLDesc *ldap_url = NULL;
    int ldap_result = 0;
    LDAPMessage *ldap_msg = NULL;
    int i;
    int entries;

    /* get db instance / connection */
#ifdef ISC_PLATFORM_USETHREADS

    /* find an available DBI from the list */
    dbi = ldap_find_avail_conn((db_list_t *)
                   ((ldap_instance_t *)dbdata)->db);

#else /* ISC_PLATFORM_USETHREADS */

    /*
     * only 1 DBI - no need to lock instance lock either
     * only 1 thread in the whole process, no possible contention.
     */
    dbi =  (dbinstance_t *) ((ldap_instance_t *)dbdata)->db;

#endif /* ISC_PLATFORM_USETHREADS */

    /* if DBI is null, can't do anything else */
    if (dbi == NULL)
        return (ISC_R_FAILURE);

    /* set fields */
    if (zone != NULL) {
        dbi->zone = isc_mem_strdup(ns_g_mctx, zone);
        if (dbi->zone == NULL) {
            result = ISC_R_NOMEMORY;
            goto cleanup;
        }
    } else {
        dbi->zone = NULL;
    }
    if (record != NULL) {
        dbi->record = isc_mem_strdup(ns_g_mctx, record);
        if (dbi->record == NULL) {
            result = ISC_R_NOMEMORY;
            goto cleanup;
        }
    } else {
        dbi->record = NULL;
    }
    if (client != NULL) {
        dbi->client = isc_mem_strdup(ns_g_mctx, client);
        if (dbi->client == NULL) {
            result = ISC_R_NOMEMORY;
            goto cleanup;
        }
    } else {
        dbi->client = NULL;
    }

    /* what type of query are we going to run? */
    switch(query) {
    case ALLNODES:
        /*
         * if the query was not passed in from the config file
         * then we can't run it.  return not_implemented, so
         * it's like the code for that operation was never
         * built into the driver.... AHHH flexibility!!!
         */
        if (dbi->allnodes_q == NULL) {
            result = ISC_R_NOTIMPLEMENTED;
            goto cleanup;
        } else {
            querystring = build_querystring(ns_g_mctx,
            dbi->allnodes_q);
        }
        break;
    case ALLOWXFR:
        /* same as comments as ALLNODES */
        if (dbi->allowxfr_q == NULL) {
            result = ISC_R_NOTIMPLEMENTED;
            goto cleanup;
        } else {
            querystring = build_querystring(ns_g_mctx,
            dbi->allowxfr_q);
        }
        break;
    case AUTHORITY:
        /* same as comments as ALLNODES */
        if (dbi->authority_q == NULL) {
            result = ISC_R_NOTIMPLEMENTED;
            goto cleanup;
        } else {
            querystring = build_querystring(ns_g_mctx,
            dbi->authority_q);
        }
        break;
    case FINDZONE:
        /* this is required.  It's the whole point of DLZ! */
        if (dbi->findzone_q == NULL) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
                      "No query specified for findzone.  "
                      "Findzone requires a query");
            result = ISC_R_FAILURE;
            goto cleanup;
        } else {
            querystring = build_querystring(ns_g_mctx,
            dbi->findzone_q);
        }
        break;
    case LOOKUP:
        /* this is required.  It's also a major point of DLZ! */
        if (dbi->lookup_q == NULL) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
                      "No query specified for lookup.  "
                      "Lookup requires a query");
            result = ISC_R_FAILURE;
            goto cleanup;
        } else {
            querystring = build_querystring(ns_g_mctx,
                            dbi->lookup_q);
        }
        break;
    default:
        /*
         * this should never happen.  If it does, the code is
         * screwed up!
         */
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "Incorrect query flag passed to "
                 "ldap_get_results");
        result = ISC_R_UNEXPECTED;
        goto cleanup;
    }

    /* if the querystring is null, Bummer, outta RAM.  UPGRADE TIME!!!   */
    if (querystring  == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup;
    }

    /*
     * output the full query string during debug so we can see
     * what lame error the query has.
     */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(1),
              "\nQuery String: %s\n", querystring);

        /* break URL down into it's component parts, if error cleanup */
    ldap_result = ldap_url_parse(querystring, &ldap_url);
    if (ldap_result != LDAP_SUCCESS || ldap_url == NULL) {
        result = ISC_R_FAILURE;
        goto cleanup;
    }

    for (i = 0; i < 3; i++) {

        /*
         * dbi->dbconn may be null if trying to reconnect on a
         * previous query failed.
         */
        if (dbi->dbconn == NULL) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_INFO,
                      "LDAP driver attempting to re-connect");

            result = dlz_ldap_connect((ldap_instance_t *) dbdata,
                          dbi);
            if (result != ISC_R_SUCCESS) {
                result = ISC_R_FAILURE;
                continue;
            }
        }

        /* perform ldap search syncronously */
        ldap_result = ldap_search_s((LDAP *) dbi->dbconn,
                        ldap_url->lud_dn,
                        ldap_url->lud_scope,
                        ldap_url->lud_filter,
                        ldap_url->lud_attrs, 0, &ldap_msg);

        /*
         * check return code.  No such object is ok, just
         * didn't find what we wanted
         */
        switch(ldap_result) {
        case LDAP_NO_SUCH_OBJECT:
                isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(1),
                      "No object found matching "
                      "query requirements");
            result = ISC_R_NOTFOUND;
            goto cleanup;
            break;
        case LDAP_SUCCESS:  /* on success do nothing */
            result = ISC_R_SUCCESS;
            i = 3;
            break;
        case LDAP_SERVER_DOWN:
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_INFO,
                      "LDAP driver attempting to re-connect");
            result = dlz_ldap_connect((ldap_instance_t *) dbdata,
                          dbi);
            if (result != ISC_R_SUCCESS)
                result = ISC_R_FAILURE;
            break;
        default:
            /*
             * other errors not ok.  Log error message and
             * get out
             */
                isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP error: %s",
                      ldap_err2string(ldap_result));
            result = ISC_R_FAILURE;
            goto cleanup;
            break;
        } /* close switch(ldap_result) */
    } /* end for (int i = 0 i < 3; i++) */

    if (result != ISC_R_SUCCESS)
        goto cleanup;

    switch(query) {
    case ALLNODES:
        result = ldap_process_results((LDAP *) dbi->dbconn, ldap_msg,
                          ldap_url->lud_attrs,
                          ptr, isc_boolean_true);
        break;
    case AUTHORITY:
    case LOOKUP:
        result = ldap_process_results((LDAP *) dbi->dbconn, ldap_msg,
                          ldap_url->lud_attrs,
                          ptr, isc_boolean_false);
        break;
    case ALLOWXFR:
        entries = ldap_count_entries((LDAP *) dbi->dbconn, ldap_msg);
        if (entries == 0)
            result = ISC_R_NOPERM;
        else if (entries > 0)
            result = ISC_R_SUCCESS;
        else
            result = ISC_R_FAILURE;
        break;
    case FINDZONE:
        entries = ldap_count_entries((LDAP *) dbi->dbconn, ldap_msg);
        if (entries == 0)
            result = ISC_R_NOTFOUND;
        else if (entries > 0)
            result = ISC_R_SUCCESS;
        else
            result = ISC_R_FAILURE;
        break;
    default:
        /*
         * this should never happen.  If it does, the code is
         * screwed up!
         */
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "Incorrect query flag passed to "
                 "ldap_get_results");
        result = ISC_R_UNEXPECTED;
    }

 cleanup:
    /* it's always good to cleanup after yourself */

        /* if we retrieved results, free them */
    if (ldap_msg != NULL)
        ldap_msgfree(ldap_msg);

    if (ldap_url != NULL)
        ldap_free_urldesc(ldap_url);

    /* cleanup */
    if (dbi->zone != NULL)
        isc_mem_free(ns_g_mctx, dbi->zone);
    if (dbi->record != NULL)
        isc_mem_free(ns_g_mctx, dbi->record);
    if (dbi->client != NULL)
        isc_mem_free(ns_g_mctx, dbi->client);

#ifdef ISC_PLATFORM_USETHREADS

    /* release the lock so another thread can use this dbi */
    isc_mutex_unlock(&dbi->instance_lock);

#endif /* ISC_PLATFORM_USETHREADS */

        /* release query string */
    if (querystring  != NULL)
        isc_mem_free(ns_g_mctx, querystring );

    /* return result */
    return (result);
}

/*
 * DLZ methods
 */
static isc_result_t
dlz_ldap_allowzonexfr(void *driverarg, void *dbdata, const char *name,
              const char *client)
{
    isc_result_t result;

    UNUSED(driverarg);

    /* check to see if we are authoritative for the zone first */
    result = dlz_ldap_findzone(driverarg, dbdata, name, NULL, NULL);
    if (result != ISC_R_SUCCESS) {
        return (result);
    }

        /* get all the zone data */
    result = ldap_get_results(name, NULL, client, ALLOWXFR, dbdata, NULL);
    return (result);
}

static isc_result_t
dlz_ldap_allnodes(const char *zone, void *driverarg, void *dbdata,
          dns_sdlzallnodes_t *allnodes)
{
    UNUSED(driverarg);
    return (ldap_get_results(zone, NULL, NULL, ALLNODES, dbdata, allnodes));
}

static isc_result_t
dlz_ldap_authority(const char *zone, void *driverarg, void *dbdata,
           dns_sdlzlookup_t *lookup)
{
    UNUSED(driverarg);
    return (ldap_get_results(zone, NULL, NULL, AUTHORITY, dbdata, lookup));
}

static isc_result_t
dlz_ldap_findzone(void *driverarg, void *dbdata, const char *name,
          dns_clientinfomethods_t *methods,
          dns_clientinfo_t *clientinfo)
{
    UNUSED(driverarg);
    UNUSED(methods);
    UNUSED(clientinfo);
    return (ldap_get_results(name, NULL, NULL, FINDZONE, dbdata, NULL));
}

static isc_result_t
dlz_ldap_lookup(const char *zone, const char *name, void *driverarg,
        void *dbdata, dns_sdlzlookup_t *lookup,
        dns_clientinfomethods_t *methods, dns_clientinfo_t *clientinfo)
{
    isc_result_t result;

    UNUSED(driverarg);
    UNUSED(methods);
    UNUSED(clientinfo);

    if (strcmp(name, "*") == 0)
        result = ldap_get_results(zone, "~", NULL, LOOKUP,
                      dbdata, lookup);
    else
        result = ldap_get_results(zone, name, NULL, LOOKUP,
                      dbdata, lookup);
    return (result);
}


static isc_result_t
dlz_ldap_create(const char *dlzname, unsigned int argc, char *argv[],
        void *driverarg, void **dbdata)
{
    isc_result_t result;
    ldap_instance_t *ldap_inst = NULL;
    dbinstance_t *dbi = NULL;
    int protocol;
    int method;

#ifdef ISC_PLATFORM_USETHREADS
    /* if multi-threaded, we need a few extra variables. */
    int dbcount;
    char *endp;
/* db_list_t *dblist = NULL; */
    int i;

#endif /* ISC_PLATFORM_USETHREADS */

    UNUSED(dlzname);
    UNUSED(driverarg);

#ifdef ISC_PLATFORM_USETHREADS
    /* if debugging, let user know we are multithreaded. */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(1),
              "LDAP driver running multithreaded");
#else /* ISC_PLATFORM_USETHREADS */
    /* if debugging, let user know we are single threaded. */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(1),
              "LDAP driver running single threaded");
#endif /* ISC_PLATFORM_USETHREADS */

    if (argc < 9) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "LDAP driver requires at least "
                  "8 command line args.");
        return (ISC_R_FAILURE);
    }

    /* no more than 13 arg's should be passed to the driver */
    if (argc > 12) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "LDAP driver cannot accept more than "
                  "11 command line args.");
        return (ISC_R_FAILURE);
    }

    /* determine protocol version. */
    if (strncasecmp(argv[2], V2, strlen(V2)) == 0) {
        protocol = 2;
    } else if (strncasecmp(argv[2], V3, strlen(V3)) == 0) {
        protocol = 3;
    } else {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "LDAP driver protocol must be either %s or %s",
                  V2, V3);
        return (ISC_R_FAILURE);
    }

    /* determine connection method. */
    if (strncasecmp(argv[3], SIMPLE, strlen(SIMPLE)) == 0) {
        method = LDAP_AUTH_SIMPLE;
    } else if (strncasecmp(argv[3], KRB41, strlen(KRB41)) == 0) {
        method = LDAP_AUTH_KRBV41;
    } else if (strncasecmp(argv[3], KRB42, strlen(KRB42)) == 0) {
        method = LDAP_AUTH_KRBV42;
    } else {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "LDAP driver authentication method must be "
                  "one of %s, %s or %s",
                  SIMPLE, KRB41, KRB42);
        return (ISC_R_FAILURE);
    }

    /* multithreaded build can have multiple DB connections */
#ifdef ISC_PLATFORM_USETHREADS

    /* check how many db connections we should create */
    dbcount = strtol(argv[1], &endp, 10);
    if (*endp != '\0' || dbcount < 0) {
        isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                  DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                  "LDAP driver database connection count "
                  "must be positive.");
        return (ISC_R_FAILURE);
    }
#endif

    /* check that LDAP URL parameters make sense */
    switch(argc) {
    case 12:
        result = dlz_ldap_checkURL(argv[11], 0, "allow zone transfer");
        if (result != ISC_R_SUCCESS)
            return (result);
    case 11:
        result = dlz_ldap_checkURL(argv[10], 3, "all nodes");
        if (result != ISC_R_SUCCESS)
            return (result);
    case 10:
        if (strlen(argv[9]) > 0) {
            result = dlz_ldap_checkURL(argv[9], 3, "authority");
            if (result != ISC_R_SUCCESS)
                return (result);
        }
    case 9:
        result = dlz_ldap_checkURL(argv[8], 3, "lookup");
        if (result != ISC_R_SUCCESS)
            return (result);
        result = dlz_ldap_checkURL(argv[7], 0, "find zone");
        if (result != ISC_R_SUCCESS)
            return (result);
        break;
    default:
        /* not really needed, should shut up compiler. */
        result = ISC_R_FAILURE;
    }

    /* allocate memory for LDAP instance */
    ldap_inst = isc_mem_get(ns_g_mctx, sizeof(ldap_instance_t));
    if (ldap_inst == NULL)
        return (ISC_R_NOMEMORY);
    memset(ldap_inst, 0, sizeof(ldap_instance_t));

    /* store info needed to automatically re-connect. */
    ldap_inst->protocol = protocol;
    ldap_inst->method = method;
    ldap_inst->hosts = isc_mem_strdup(ns_g_mctx, argv[6]);
    if (ldap_inst->hosts == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup;
    }
    ldap_inst->user = isc_mem_strdup(ns_g_mctx, argv[4]);
    if (ldap_inst->user == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup;
    }
    ldap_inst->cred = isc_mem_strdup(ns_g_mctx, argv[5]);
    if (ldap_inst->cred == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup;
    }

#ifdef ISC_PLATFORM_USETHREADS
    /* allocate memory for database connection list */
    ldap_inst->db = isc_mem_get(ns_g_mctx, sizeof(db_list_t));
    if (ldap_inst->db == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup;
    }

    /* initialize DB connection list */
    ISC_LIST_INIT(*(ldap_inst->db));

    /*
     * create the appropriate number of database instances (DBI)
     * append each new DBI to the end of the list
     */
    for (i = 0; i < dbcount; i++) {

#endif /* ISC_PLATFORM_USETHREADS */

        /* how many queries were passed in from config file? */
        switch(argc) {
        case 9:
            result = build_sqldbinstance(ns_g_mctx, NULL, NULL,
                             NULL, argv[7], argv[8],
                             NULL, &dbi);
            break;
        case 10:
            result = build_sqldbinstance(ns_g_mctx, NULL, NULL,
                             argv[9], argv[7], argv[8],
                             NULL, &dbi);
            break;
        case 11:
            result = build_sqldbinstance(ns_g_mctx, argv[10], NULL,
                             argv[9], argv[7], argv[8],
                             NULL, &dbi);
            break;
        case 12:
            result = build_sqldbinstance(ns_g_mctx, argv[10],
                             argv[11], argv[9],
                             argv[7], argv[8],
                             NULL, &dbi);
            break;
        default:
            /* not really needed, should shut up compiler. */
            result = ISC_R_FAILURE;
        }

        if (result == ISC_R_SUCCESS) {
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
                      "LDAP driver created "
                      "database instance object.");
        } else { /* unsuccessful?, log err msg and cleanup. */
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not create "
                      "database instance object.");
            goto cleanup;
        }

#ifdef ISC_PLATFORM_USETHREADS
        /* when multithreaded, build a list of DBI's */
        ISC_LINK_INIT(dbi, link);
        ISC_LIST_APPEND(*(ldap_inst->db), dbi, link);
#else
        /*
         * when single threaded, hold onto the one connection
         * instance.
         */
        ldap_inst->db = dbi;

#endif
        /* attempt to connect */
        result = dlz_ldap_connect(ldap_inst, dbi);

        /*
         * if db connection cannot be created, log err msg and
         * cleanup.
         */
        switch(result) {
            /* success, do nothing */
        case ISC_R_SUCCESS:
            break;
            /*
             * no memory means ldap_init could not
             * allocate memory
             */
        case ISC_R_NOMEMORY:
#ifdef ISC_PLATFORM_USETHREADS
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not allocate memory "
                      "for connection number %u",
                      i+1);
#else
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not allocate memory "
                      "for connection");
#endif
            goto cleanup;
            break;
            /*
             * no perm means ldap_set_option could not set
             * protocol version
             */
        case ISC_R_NOPERM:
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not "
                      "set protocol version.");
            result = ISC_R_FAILURE;
            goto cleanup;
            break;
            /* failure means couldn't connect to ldap server */
        case ISC_R_FAILURE:
#ifdef ISC_PLATFORM_USETHREADS
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not "
                      "bind connection number %u to server.",
                      i+1);
#else
            isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
                      DNS_LOGMODULE_DLZ, ISC_LOG_ERROR,
                      "LDAP driver could not "
                      "bind connection to server.");
#endif
            goto cleanup;
            break;
            /*
             * default should never happen.  If it does,
             * major errors.
             */
        default:
            UNEXPECTED_ERROR(__FILE__, __LINE__,
                     "dlz_ldap_create() failed: %s",
                     isc_result_totext(result));
            result = ISC_R_UNEXPECTED;
            goto cleanup;
            break;
        } /* end switch(result) */


#ifdef ISC_PLATFORM_USETHREADS

        /* set DBI = null for next loop through. */
        dbi = NULL;
    }   /* end for loop */

#endif /* ISC_PLATFORM_USETHREADS */


    /* set dbdata to the ldap_instance we created. */
    *dbdata = ldap_inst;

    /* hey, we got through all of that ok, return success. */
    return(ISC_R_SUCCESS);

 cleanup:
    dlz_ldap_destroy(NULL, ldap_inst);

    return(ISC_R_FAILURE);
}

void
dlz_ldap_destroy(void *driverarg, void *dbdata) {
    UNUSED(driverarg);

    if (dbdata != NULL) {
#ifdef ISC_PLATFORM_USETHREADS
        /* cleanup the list of DBI's */
        ldap_destroy_dblist((db_list_t *)
                    ((ldap_instance_t *)dbdata)->db);

#else /* ISC_PLATFORM_USETHREADS */
        if (((ldap_instance_t *)dbdata)->db->dbconn != NULL)
            ldap_unbind_s((LDAP *)
                      ((ldap_instance_t *)dbdata)->db->dbconn);

        /* destroy single DB instance */
        destroy_sqldbinstance(((ldap_instance_t *)dbdata)->db);
#endif /* ISC_PLATFORM_USETHREADS */

        if (((ldap_instance_t *)dbdata)->hosts != NULL)
            isc_mem_free(ns_g_mctx,
                     ((ldap_instance_t *)dbdata)->hosts);

        if (((ldap_instance_t *)dbdata)->user != NULL)
            isc_mem_free(ns_g_mctx,
                     ((ldap_instance_t *)dbdata)->user);

        if (((ldap_instance_t *)dbdata)->cred != NULL)
            isc_mem_free(ns_g_mctx,
                     ((ldap_instance_t *)dbdata)->cred);

        isc_mem_put(ns_g_mctx, dbdata, sizeof(ldap_instance_t));
    }
}

static dns_sdlzmethods_t dlz_ldap_methods = {
    dlz_ldap_create,
    dlz_ldap_destroy,
    dlz_ldap_findzone,
    dlz_ldap_lookup,
    dlz_ldap_authority,
    dlz_ldap_allnodes,
    dlz_ldap_allowzonexfr,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
};

/*%
 * Wrapper around dns_sdlzregister().
 */
isc_result_t
dlz_ldap_init(void) {
    isc_result_t result;

    /*
     * Write debugging message to log
     */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
              "Registering DLZ ldap driver.");

    result = dns_sdlzregister("ldap", &dlz_ldap_methods, NULL,
                  DNS_SDLZFLAG_RELATIVEOWNER |
                  DNS_SDLZFLAG_RELATIVERDATA,
                  ns_g_mctx, &dlz_ldap);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "dns_sdlzregister() failed: %s",
                 isc_result_totext(result));
        result = ISC_R_UNEXPECTED;
    }

    return (result);
}

/*%
 * Wrapper around dns_sdlzunregister().
 */
void
dlz_ldap_clear(void) {
    /*
     * Write debugging message to log
     */
    isc_log_write(dns_lctx, DNS_LOGCATEGORY_DATABASE,
              DNS_LOGMODULE_DLZ, ISC_LOG_DEBUG(2),
              "Unregistering DLZ ldap driver.");

    if (dlz_ldap != NULL)
        dns_sdlzunregister(&dlz_ldap);
}

#endif