/** BEGIN COPYRIGHT BLOCK
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 *
 * License: GPL (version 3 or any later version).
 * See LICENSE for details.
 * END COPYRIGHT BLOCK **/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "cb.h"

/*
 * Most of the complicated connection-related code lives in this file.  Some
 * general notes about how we manage our connections to "remote" LDAP servers:
 *
 * 1) Each farm server we have a relationship with is managed independently.
 *
 * 2) We may simultaneously issue multiple requests on a single LDAP
 *    connection.  Each server has a "maxconcurrency" configuration
 *    parameter associated with it that caps the number of outstanding operations
 *    per connection.  For each connection we maintain a "usecount"
 *    which is used to track the number of threads using the connection.
 *
 * 3) IMPORTANT NOTE: This connexion management is stateless i.e there is no garanty that
 *    operation from the same incoming client connections are sent to the same
 *    outgoing connection to the farm server. Today, this is not a problem because
 *    all controls we support are stateless. The implementation of the abandon
 *    operation takes this limitation into account.
 *
 * 4) We may open more than one connection to a server. Each farm server
 *    has a "maxconnections" configuration parameter associated with it
 *    that caps the number of connections.
 *
 * 5) If no connection is available to service a request , threads
 *    go to sleep on a condition variable and one is woken up each time
 *    a connection's "usecount" is decremented.
 *
 * 6) If we see an LDAP_CONNECT_ERROR or LDAP_SERVER_DOWN error on a
 *    session handle, we mark its status as CB_LDAP_STATUS_DOWN and
 *    close it as soon as all threads using it release it.  Connections
 *    marked as "down" are not counted against the "maxconnections" limit.
 *
 * 7) We close and reopen connections that have been open for more than
 *    the server's configured connection lifetime.  This is done to ensure
 *    that we reconnect to a primary server after failover occurs.  If no
 *    lifetime is configured or it is set to 0, we never close and reopen
 *    connections.
 */

static void cb_close_and_dispose_connection(cb_outgoing_conn *conn);
static void cb_check_for_stale_connections(cb_conn_pool *pool);

PRUint32 PR_GetThreadID(PRThread *thread);

/* returns the threadId of the current thread modulo MAX_CONN_ARRAY
=> gives the position of the thread in the array of secure connections */
static int
PR_ThreadSelf(void)
{
    PRThread *thr = PR_GetCurrentThread();
    PRUint32 myself = PR_GetThreadID(thr);
    myself &= 0x000007FF;
    return myself;
}

static int
PR_MyThreadId(void)
{
    PRThread *thr = PR_GetCurrentThread();
    PRUint32 myself = PR_GetThreadID(thr);
    return myself;
}

/*
** Close outgoing connections
*/

void
cb_close_conn_pool(cb_conn_pool *pool)
{

    cb_outgoing_conn *conn, *nextconn;
    int secure = pool->secure;
    int i = 0;

    slapi_lock_mutex(pool->conn.conn_list_mutex);

    if (secure) {
        for (i = 0; i < MAX_CONN_ARRAY; i++) {
            for (conn = pool->connarray[i]; conn != NULL; conn = nextconn) {
                if (conn->status != CB_CONNSTATUS_OK) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_close_conn_pool - Unexpected connection state (%d)\n", conn->status);
                }
                nextconn = conn->next;
                cb_close_and_dispose_connection(conn);
            }
        }
    } else {
        for (conn = pool->conn.conn_list; conn != NULL; conn = nextconn) {
            if (conn->status != CB_CONNSTATUS_OK) {
                slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                              "cb_close_conn_pool - Unexpected connection state (%d)\n", conn->status);
            }
            nextconn = conn->next;
            cb_close_and_dispose_connection(conn);
        }
    }

    pool->conn.conn_list = NULL;
    pool->conn.conn_list_count = 0;

    slapi_unlock_mutex(pool->conn.conn_list_mutex);
}

/*
 * Get an LDAP session handle for communicating with the farm servers.
 *
 * Returns an LDAP eror code, typically:
 *      LDAP_SUCCESS
 *      LDAP_TIMELIMIT_EXCEEDED
 *      LDAP_CONNECT_ERROR
 * NOTE : if maxtime NULL, use operation timeout
 */

int
cb_get_connection(cb_conn_pool *pool,
                  LDAP **lld,
                  cb_outgoing_conn **cc,
                  struct timespec *expire_time,
                  char **errmsg)
{
    int rc = LDAP_SUCCESS; /* optimistic */
    cb_outgoing_conn *conn = NULL;
    cb_outgoing_conn *connprev = NULL;
    LDAP *ld = NULL;
    int checktime = 0;
    struct timeval bind_to, op_to;
    unsigned int maxconcurrency, maxconnections;
    char *password, *binddn, *hostname;
    unsigned int port;
    int secure;
    char *mech = NULL;
    ;
    static char *error1 = "Can't contact remote server : %s";
    int isMultiThread = ENABLE_MULTITHREAD_PER_CONN; /* by default, we enable multiple operations per connection */

    struct timespec cb_expire_time;

    /*
    ** return an error if we can't get a connection
    ** before the operation timeout has expired
        ** bind_timeout: timeout for the bind operation (if bind needed)
    **   ( checked in ldap_result )
    ** op_timeout: timeout for the op that needs a connection
    **   ( checked in the loop )
    */
    *cc = NULL;

    slapi_rwlock_rdlock(pool->rwl_config_lock);
    maxconcurrency = pool->conn.maxconcurrency;
    maxconnections = pool->conn.maxconnections;
    bind_to.tv_sec = pool->conn.bind_timeout.tv_sec;
    bind_to.tv_usec = pool->conn.bind_timeout.tv_usec;
    op_to.tv_sec = pool->conn.op_timeout.tv_sec;
    op_to.tv_usec = pool->conn.op_timeout.tv_usec;

    /* SD 02/10/2000 temp fix                        */
    /* allow dynamic update of the binddn & password */
    /* host, port and security mode             */
    /* previous values are NOT freed when changed    */
    /* won't likely to be changed often         */
    /* pointers put in the waste basket fields and   */
    /* freed when the backend is stopped.            */

    password = pool->password;
    binddn = pool->binddn;
    hostname = pool->hostname;
    port = pool->port;
    secure = pool->secure;
    if (pool->starttls) {
        secure = 2;
    }
    mech = pool->mech;

    slapi_rwlock_unlock(pool->rwl_config_lock);

    if (secure) {
        isMultiThread = DISABLE_MULTITHREAD_PER_CONN;
    }

    /* For stupid admins */
    if (maxconnections <= 0) {
        static int warned_maxconn = 0;
        if (!warned_maxconn) {
            slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - Error (no connection available)\n");
            warned_maxconn = 1;
        }
        if (errmsg) {
            *errmsg = slapi_ch_smprintf("%s", ENDUSERMSG);
        }
        return LDAP_CONNECT_ERROR;
    }

    if (expire_time) {
        if (expire_time->tv_sec > 0) {
            checktime = 1;

            cb_expire_time.tv_sec = expire_time->tv_sec;
            cb_expire_time.tv_nsec = expire_time->tv_nsec;

            /* make sure bind to <= operation timeout */
            if ((bind_to.tv_sec == 0) || (bind_to.tv_sec > expire_time->tv_sec)) {
                bind_to.tv_sec = expire_time->tv_sec;
            }
        }
    } else {
        if (op_to.tv_sec != 0) {
            checktime = 1;
            slapi_timespec_expire_at(op_to.tv_sec, &cb_expire_time);

            /* make sure bind to <= operation timeout */
            if ((bind_to.tv_sec == 0) || (bind_to.tv_sec > op_to.tv_sec)) {
                bind_to.tv_sec = op_to.tv_sec;
            }
        }
    }

    /*
     * Close (or mark to be closed) any connections for this farm server that have
      * exceeded the maximum connection lifetime.
     */

    cb_check_for_stale_connections(pool);

    /*
     * Look for an available, already open connection
     */

    slapi_lock_mutex(pool->conn.conn_list_mutex);

    if (cb_debug_on()) {
        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                      "cb_get_connection - server %s conns: %d maxconns: %d\n",
                      hostname, pool->conn.conn_list_count, maxconnections);
    }

    for (;;) {

        /* time limit mgmt */
        if (checktime && slapi_timespec_expire_check(&cb_expire_time) == TIMER_EXPIRED) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - server %s expired.\n", hostname);
            if (errmsg) {
                *errmsg = PR_smprintf(error1, "timelimit exceeded");
            }
            rc = LDAP_TIMELIMIT_EXCEEDED;
            conn = NULL;
            ld = NULL;
            goto unlock_and_return;
        }

        /*
         * First, look for an available, already open/bound connection
         */

        if (secure) {
            for (conn = pool->connarray[PR_ThreadSelf()]; conn != NULL; conn = conn->next) {
                if ((conn->ThreadId == PR_MyThreadId()) && (conn->status == CB_CONNSTATUS_OK &&
                                                            conn->refcount < maxconcurrency)) {
                    if (cb_debug_on()) {
                        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                      "cb_get_connection - server found conn 0x%p to use)\n", conn);
                    }
                    goto unlock_and_return; /* found one */
                }
            }
        } else {
            connprev = NULL;
            for (conn = pool->conn.conn_list; conn != NULL; conn = conn->next) {
                if (cb_debug_on()) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_get_connection - conn 0x%p status %d refcount %lu\n", conn,
                                  conn->status, conn->refcount);
                }

                if (conn->status == CB_CONNSTATUS_OK && conn->refcount < maxconcurrency) {
                    if (cb_debug_on()) {
                        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                      "cb_get_connection - server found conn 0x%p to use)\n", conn);
                    }
                    goto unlock_and_return; /* found one */
                }
                connprev = conn;
            }
        }

        if (secure || pool->conn.conn_list_count < maxconnections) {

            int version = LDAP_VERSION3;

            /*
                      * we have not exceeded the maximum number of connections allowed,
                      * so we initialize a new one and add it to the end of our list.
                      */

            /* No need to lock. url can't be changed dynamically */
            ld = slapi_ldap_init(hostname, port, secure, isMultiThread);
            if (NULL == ld) {
                static int warned_init = 0;
                if (!warned_init) {
                    slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                  "cb_get_connection -  Can't contact server <%s> port <%d>.\n",
                                  hostname, port);
                    warned_init = 1;
                }
                if (errmsg) {
                    *errmsg = slapi_ch_smprintf("%s", ENDUSERMSG);
                }
                rc = LDAP_CONNECT_ERROR;
                goto unlock_and_return;
            }

            ldap_set_option(ld, LDAP_OPT_PROTOCOL_VERSION, &version);
            /* Don't chase referrals */
            ldap_set_option(ld, LDAP_OPT_REFERRALS, LDAP_OPT_OFF);

            /* no controls and simple bind only */
            /* For now, bind even if no user to detect error */
            /* earlier                     */
            if (pool->bindit) {
                PRErrorCode prerr = 0;
                LDAPControl **serverctrls = NULL;

                char *plain = NULL;
                int ret = -1;

                rc = LDAP_SUCCESS;

                if (cb_debug_on()) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_get_connection - Bind to to server <%s> port <%d> as <%s>\n",
                                  hostname, port, binddn);
                }

                ret = pw_rever_decode(password, &plain, CB_CONFIG_USERPASSWORD);

                /* Pb occured in decryption: stop now, binding will fail */
                if (ret == -1) {
                    static int warned_pw = 0;
                    if (!warned_pw) {
                        slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                      "cb_get_connection - Internal credentials decoding error; "
                                      "password storage schemes do not match or "
                                      "encrypted password is corrupted.\n");
                        warned_pw = 1;
                    }
                    if (errmsg) {
                        *errmsg = slapi_ch_smprintf("%s", ENDUSERMSG);
                    }
                    rc = LDAP_INVALID_CREDENTIALS;
                    goto unlock_and_return;
                }

                /* Password-based client authentication */
                rc = slapi_ldap_bind(ld, binddn, plain, mech, NULL, &serverctrls,
                                     &bind_to, NULL);

                if (ret == 0)
                    slapi_ch_free_string(&plain); /* free plain only if it has been duplicated */

                if (rc == LDAP_TIMEOUT) {
                    static int warned_bind_timeout = 0;
                    if (!warned_bind_timeout) {
                        slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                      "cb_get_connection - Can't bind to server <%s> port <%d>. (%s)\n",
                                      hostname, port, "time-out expired");
                        warned_bind_timeout = 1;
                    }
                    if (errmsg) {
                        *errmsg = slapi_ch_smprintf("%s", ENDUSERMSG);
                    }
                    rc = LDAP_CONNECT_ERROR;
                    goto unlock_and_return;
                } else if (rc != LDAP_SUCCESS) {
                    prerr = PR_GetError();
                    static int warned_bind_err = 0;
                    if (!warned_bind_err) {
                        slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                      "cb_get_connection - Can't bind to server <%s> port <%d>. "
                                      "(LDAP error %d - %s; " SLAPI_COMPONENT_NAME_NSPR " error %d - %s)\n",
                                      hostname, port, rc,
                                      ldap_err2string(rc),
                                      prerr, slapd_pr_strerror(prerr));
                        warned_bind_err = 1;
                    }
                    if (errmsg) {
                        *errmsg = slapi_ch_smprintf("%s", ENDUSERMSG);
                    }
                    rc = LDAP_CONNECT_ERROR;
                    goto unlock_and_return;
                }

                if (serverctrls) {
                    int i;
                    for (i = 0; serverctrls[i] != NULL; ++i) {
                        if (!(strcmp(serverctrls[i]->ldctl_oid, LDAP_CONTROL_PWEXPIRED))) {
                            /* Bind is successful but password has expired */
                            slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                          "cb_get_connection - Successfully bound as %s to remote server %s:%d, "
                                          "but password has expired.\n",
                                          binddn, hostname, port);
                        } else if (!(strcmp(serverctrls[i]->ldctl_oid, LDAP_CONTROL_PWEXPIRING))) {
                            /* The password is expiring in n seconds */
                            if ((serverctrls[i]->ldctl_value.bv_val != NULL) &&
                                (serverctrls[i]->ldctl_value.bv_len > 0)) {
                                int password_expiring = atoi(serverctrls[i]->ldctl_value.bv_val);
                                slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                              "cb_get_connection - Successfully bound as %s to remote server %s:%d, "
                                              "but password is expiring in %d seconds.\n",
                                              binddn, hostname, port, password_expiring);
                            }
                        }
                    }
                    ldap_controls_free(serverctrls);
                }
            } else if (secure == 2) {
                /* the start_tls operation is usually performed in slapi_ldap_bind, but
                   since we are not binding we still need to start_tls */
                if (cb_debug_on()) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_get_connection - doing start_tls on connection 0x%p\n", conn);
                }
                if ((rc = ldap_start_tls_s(ld, NULL, NULL))) {
                    PRErrorCode prerr = PR_GetError();
                    slapi_log_err(SLAPI_LOG_ERR, CB_PLUGIN_SUBSYSTEM,
                                  "cb_get_connection - Unable to do start_tls on connection to %s:%d "
                                  "LDAP error %d:%s NSS error %d:%s\n",
                                  hostname, port,
                                  rc, ldap_err2string(rc), prerr,
                                  slapd_pr_strerror(prerr));

                    goto unlock_and_return;
                }
            }

            conn = (cb_outgoing_conn *)slapi_ch_malloc(sizeof(cb_outgoing_conn));
            conn->ld = ld;
            conn->status = CB_CONNSTATUS_OK;
            conn->refcount = 0; /* incremented below */
            conn->opentime = slapi_current_rel_time_t();
            conn->ThreadId = PR_MyThreadId(); /* store the thread id */
            conn->next = NULL;
            if (secure) {
                if (pool->connarray[PR_ThreadSelf()] == NULL) {
                    pool->connarray[PR_ThreadSelf()] = conn;
                } else {
                    conn->next = pool->connarray[PR_ThreadSelf()];
                    pool->connarray[PR_ThreadSelf()] = conn;
                }
            } else {
                if (NULL == connprev) {
                    pool->conn.conn_list = conn;
                } else {
                    connprev->next = conn;
                }
            }

            ++pool->conn.conn_list_count;

            if (cb_debug_on()) {
                slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                              "cb_get_connection - added new conn 0x%p, "
                              "conn count now %d\n",
                              conn->ld, pool->conn.conn_list_count);
            }
            goto unlock_and_return; /* got a new one */
        }

        if (cb_debug_on()) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - waiting for conn to free up\n");
        }

        if (!secure)
            slapi_wait_condvar_pt(pool->conn.conn_list_cv, pool->conn.conn_list_mutex, NULL);

        if (cb_debug_on()) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - awake again\n");
        }
    }

unlock_and_return:
    if (conn != NULL) {
        ++conn->refcount;
        *lld = conn->ld;
        *cc = conn;
        if (cb_debug_on()) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - ld=0x%p (concurrency now %lu)\n", *lld, conn->refcount);
        }

    } else {
        if (NULL != ld) {
            slapi_ldap_unbind(ld);
        }

        if (cb_debug_on()) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_get_connection - error %d\n", rc);
        }
    }

    slapi_unlock_mutex(pool->conn.conn_list_mutex);
    return (rc);
}

/*
 * We are done with the connection handle because the
 * LDAP operation has completed.
 */

void
cb_release_op_connection(cb_conn_pool *pool, LDAP *lld, int dispose)
{

    cb_outgoing_conn *conn;
    cb_outgoing_conn *connprev = NULL;
    int secure = pool->secure;
    int myself = 0;

    slapi_lock_mutex(pool->conn.conn_list_mutex);
    /*
          * find the connection structure this ld is part of
         */

    if (secure) {
        myself = PR_ThreadSelf();
        for (conn = pool->connarray[myself]; conn != NULL; conn = conn->next) {
            if (lld == conn->ld)
                break;
            connprev = conn;
        }
    } else {
        for (conn = pool->conn.conn_list; conn != NULL; conn = conn->next) {
            if (lld == conn->ld)
                break;
            connprev = conn;
        }
    }

    if (conn == NULL) { /* ld not found -- unexpected */
        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                      "cb_release_op_connection - ld=0x%p not found\n", lld);
    } else {

        --conn->refcount;

        if (cb_debug_on()) {
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_release_op_connection - release conn 0x%p status %d refcount after release %lu\n", conn,
                          conn->status, conn->refcount);
        }

        if (dispose) {
            conn->status = CB_CONNSTATUS_DOWN;
        }

        if (conn->status != CB_CONNSTATUS_OK && conn->refcount == 0) {

            /*
                      * remove from server's connection list
                       */

            if (!secure) {
                if (connprev == NULL) {
                    pool->conn.conn_list = conn->next;
                } else {
                    connprev->next = conn->next;
                }
            } else {
                if (connprev == NULL) {
                    pool->connarray[myself] = conn->next;
                } else {
                    connprev->next = conn->next;
                }
            }

            --pool->conn.conn_list_count;

            /*
                      * close connection and free memory
                      */
            cb_close_and_dispose_connection(conn);
        }
    }

    /*
          * wake up a thread that is waiting for a connection
     */

    if (!secure)
        slapi_notify_condvar(pool->conn.conn_list_cv, 0);

    slapi_unlock_mutex(pool->conn.conn_list_mutex);
}


static void
cb_close_and_dispose_connection(cb_outgoing_conn *conn)
{
    slapi_ldap_unbind(conn->ld);
    conn->ld = NULL;
    slapi_ch_free((void **)&conn);
}

static void
cb_check_for_stale_connections(cb_conn_pool *pool)
{

    cb_outgoing_conn *connprev, *conn, *conn_next;
    time_t curtime;
    int connlifetime;
    int myself;

    slapi_rwlock_rdlock(pool->rwl_config_lock);
    connlifetime = pool->conn.connlifetime;
    slapi_rwlock_unlock(pool->rwl_config_lock);

    connprev = NULL;
    conn_next = NULL;

    slapi_lock_mutex(pool->conn.conn_list_mutex);

    if (connlifetime > 0)
        curtime = slapi_current_rel_time_t();

    if (pool->secure) {
        myself = PR_ThreadSelf();
        for (conn = pool->connarray[myself]; conn != NULL; conn = conn_next) {
            if ((conn->status == CB_CONNSTATUS_STALE) ||
                ((connlifetime > 0) && (curtime - conn->opentime > connlifetime))) {
                if (conn->refcount == 0) {
                    if (cb_debug_on()) {
                        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                      "cb_check_for_stale_connections - conn 0x%p idle and stale\n", conn);
                    }
                    --pool->conn.conn_list_count;
                    if (connprev == NULL) {
                        pool->connarray[myself] = conn->next;
                    } else {
                        connprev->next = conn->next;
                    }
                    conn_next = conn->next;
                    cb_close_and_dispose_connection(conn);
                    continue;
                }
                /* Connection is stale but in use                           */
                /* Mark to be disposed later but let it in the backend list */
                /* so that it is counted as a valid connection              */
                else {
                    conn->status = CB_CONNSTATUS_STALE;
                }
                if (cb_debug_on()) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_check_for_stale_connections - conn 0x%p stale\n", conn);
                }
            }
            connprev = conn;
            conn_next = conn->next;
        }
        slapi_unlock_mutex(pool->conn.conn_list_mutex);
        return;
    }

    for (conn = pool->conn.conn_list; conn != NULL; conn = conn_next) {
        if ((conn->status == CB_CONNSTATUS_STALE) ||
            ((connlifetime > 0) && (curtime - conn->opentime > connlifetime))) {
            if (conn->refcount == 0) {

                /* Connection idle & stale. Remove and free. */

                if (NULL == connprev)
                    pool->conn.conn_list = conn->next;
                else
                    connprev->next = conn->next;

                if (cb_debug_on()) {
                    slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                                  "cb_check_for_stale_connections - conn 0x%p idle and stale\n", conn);
                }
                --pool->conn.conn_list_count;
                conn_next = conn->next;
                cb_close_and_dispose_connection(conn);
                continue;
            }

            /* Connection is stale but in use                           */
            /* Mark to be disposed later but let it in the backend list */
            /* so that it is counted as a valid connection              */
            else {
                conn->status = CB_CONNSTATUS_STALE;
            }
            if (cb_debug_on()) {
                slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                              "cb_check_for_stale_connections - conn 0x%p stale\n", conn);
            }
        }
        connprev = conn;
        conn_next = conn->next;
    }

    /* Generate an event to wake up threads waiting */
    /* for a conn to be released. Useful to detect  */
    /* exceeded time limit. May be expensive        */

    slapi_notify_condvar(pool->conn.conn_list_cv, 0);

    slapi_unlock_mutex(pool->conn.conn_list_mutex);
}

/*
 * close all open connections in preparation for server shutdown, etc.
 * WARNING: Don't wait for current operations to complete
 */

void
cb_close_all_connections(Slapi_Backend *be)
{

    cb_outgoing_conn *conn, *next_conn;
    cb_backend_instance *cb = cb_get_instance(be);
    int i;

    slapi_lock_mutex(cb->pool->conn.conn_list_mutex);
    if (cb->pool->secure) {
        for (i = 0; i < MAX_CONN_ARRAY; i++) {
            for (conn = cb->pool->connarray[i]; conn != NULL; conn = next_conn) {
                next_conn = conn->next;
                cb_close_and_dispose_connection(conn);
            }
        }
    } else {
        for (conn = cb->pool->conn.conn_list; conn != NULL; conn = next_conn) {
            next_conn = conn->next;
            cb_close_and_dispose_connection(conn);
        }
    }
    slapi_unlock_mutex(cb->pool->conn.conn_list_mutex);

    slapi_lock_mutex(cb->bind_pool->conn.conn_list_mutex);
    if (cb->bind_pool->secure) {
        for (i = 0; i < MAX_CONN_ARRAY; i++) {
            for (conn = cb->bind_pool->connarray[i]; conn != NULL; conn = next_conn) {
                next_conn = conn->next;
                cb_close_and_dispose_connection(conn);
            }
        }
    } else {
        for (conn = cb->bind_pool->conn.conn_list; conn != NULL; conn = next_conn) {
            next_conn = conn->next;
            cb_close_and_dispose_connection(conn);
        }
    }
    slapi_unlock_mutex(cb->bind_pool->conn.conn_list_mutex);
}

/* Mark used connections as stale and close unsued connections */
/* Called when the target farm url has changed               */

void
cb_stale_all_connections(cb_backend_instance *cb)
{
    cb_outgoing_conn *conn, *next_conn, *prev_conn;
    int notify = 0;
    int i, j;
    cb_conn_pool *pools[3];

    pools[0] = cb->pool;
    pools[1] = cb->bind_pool;
    pools[2] = NULL;

    for (i = 0; pools[i]; i++) {
        slapi_lock_mutex(pools[i]->conn.conn_list_mutex);
        for (j = 0; j < MAX_CONN_ARRAY; j++) {
            prev_conn = NULL;
            for (conn = pools[i]->connarray[j]; conn != NULL; conn = next_conn) {
                next_conn = conn->next;
                if (conn->refcount > 0) {
                    /*
        ** Connection is stale but in use
        ** Mark to be disposed later but let it in the backend list
        ** so that it is counted as a valid connection
        */
                    conn->status = CB_CONNSTATUS_STALE;
                    prev_conn = conn;
                } else {
                    if (prev_conn == NULL) {
                        pools[i]->connarray[j] = next_conn;
                    } else {
                        prev_conn->next = next_conn;
                    }
                    cb_close_and_dispose_connection(conn);
                    pools[i]->conn.conn_list_count--;
                }
            }
        }
        prev_conn = NULL;
        for (conn = pools[i]->conn.conn_list; conn != NULL; conn = next_conn) {
            next_conn = conn->next;
            if (conn->refcount > 0) {
                /*
        ** Connection is stale but in use
        ** Mark to be disposed later but let it in the backend list
        ** so that it is counted as a valid connection
        */
                conn->status = CB_CONNSTATUS_STALE;
                prev_conn = conn;
            } else {
                if (conn == pools[i]->conn.conn_list) {
                    pools[i]->conn.conn_list = next_conn;
                } else if (prev_conn) {
                    prev_conn->next = next_conn;
                }
                cb_close_and_dispose_connection(conn);
                pools[i]->conn.conn_list_count--;
                notify = 1;
            }
        }
        if (notify && (!pools[i]->secure)) {
            slapi_notify_condvar(pools[i]->conn.conn_list_cv, 0);
        }
        slapi_unlock_mutex(pools[i]->conn.conn_list_mutex);
    }
}


/* Try to figure out if a farm server is still alive */

int
cb_ping_farm(cb_backend_instance *cb, cb_outgoing_conn *cnx, time_t end_time)
{

    char *attrs[] = {"1.1", NULL};
    int rc;
    struct timeval timeout;
    LDAP *ld;
    LDAPMessage *result;
    time_t now;
    int secure;
    if (cb->max_idle_time <= 0) /* Heart-beat disabled */
        return LDAP_SUCCESS;

    if (cnx && (cnx->status != CB_CONNSTATUS_OK)) /* Known problem */
        return LDAP_SERVER_DOWN;

    now = slapi_current_rel_time_t();
    if (end_time && ((now <= end_time) || (end_time < 0)))
        return LDAP_SUCCESS;

    secure = cb->pool->secure;
    if (cb->pool->starttls) {
        secure = 2;
    }
    ld = slapi_ldap_init(cb->pool->hostname, cb->pool->port, secure, 0);
    if (NULL == ld) {
        cb_update_failed_conn_cpt(cb);
        return LDAP_SERVER_DOWN;
    }

    timeout.tv_sec = cb->max_test_time;
    timeout.tv_usec = 0;

    /* NOTE: This will fail if we implement the ability to disable
       anonymous bind */
    rc = ldap_search_ext_s(ld, NULL, LDAP_SCOPE_BASE, "objectclass=*", attrs, 1, NULL,
                           NULL, &timeout, 1, &result);
    if (LDAP_SUCCESS != rc) {
        slapi_ldap_unbind(ld);
        cb_update_failed_conn_cpt(cb);
        return LDAP_SERVER_DOWN;
    }

    ldap_msgfree(result);
    slapi_ldap_unbind(ld);
    cb_reset_conn_cpt(cb);
    return LDAP_SUCCESS;
}


void
cb_update_failed_conn_cpt(cb_backend_instance *cb)
{
    /* if the chaining BE is already unavailable, we do nothing*/
    time_t now;
    if (cb->monitor_availability.farmserver_state == FARMSERVER_AVAILABLE) {
        slapi_lock_mutex(cb->monitor_availability.cpt_lock);
        cb->monitor_availability.cpt++;
        slapi_unlock_mutex(cb->monitor_availability.cpt_lock);
        if (cb->monitor_availability.cpt >= CB_NUM_CONN_BEFORE_UNAVAILABILITY) {
            /* we reach the limit of authorized failed connections => we setup the chaining BE state to unavailable */
            now = slapi_current_rel_time_t();
            slapi_lock_mutex(cb->monitor_availability.lock_timeLimit);
            cb->monitor_availability.unavailableTimeLimit = now + CB_UNAVAILABLE_PERIOD;
            slapi_unlock_mutex(cb->monitor_availability.lock_timeLimit);
            cb->monitor_availability.farmserver_state = FARMSERVER_UNAVAILABLE;
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_update_failed_conn_cpt - Farm server unavailable");
        }
    }
}

void
cb_reset_conn_cpt(cb_backend_instance *cb)
{
    if (cb->monitor_availability.cpt > 0) {
        slapi_lock_mutex(cb->monitor_availability.cpt_lock);
        cb->monitor_availability.cpt = 0;
        if (cb->monitor_availability.farmserver_state == FARMSERVER_UNAVAILABLE) {
            cb->monitor_availability.farmserver_state = FARMSERVER_AVAILABLE;
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_reset_conn_cpt - Farm server is back");
        }
        slapi_unlock_mutex(cb->monitor_availability.cpt_lock);
    }
}

int
cb_check_availability(cb_backend_instance *cb, Slapi_PBlock *pb)
{
    /* check wether the farmserver is available or not */
    time_t now;
    if (cb->monitor_availability.farmserver_state == FARMSERVER_UNAVAILABLE) {
        slapi_lock_mutex(cb->monitor_availability.lock_timeLimit);
        now = slapi_current_rel_time_t();
        if (now >= cb->monitor_availability.unavailableTimeLimit) {
            cb->monitor_availability.unavailableTimeLimit = now + CB_INFINITE_TIME; /* to be sure only one thread can do the test */
            slapi_unlock_mutex(cb->monitor_availability.lock_timeLimit);
        } else {
            slapi_unlock_mutex(cb->monitor_availability.lock_timeLimit);
            cb_send_ldap_result(pb, LDAP_OPERATIONS_ERROR, NULL, "FARM SERVER TEMPORARY UNAVAILABLE", 0, NULL);
            return FARMSERVER_UNAVAILABLE;
        }
        slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                      "cb_check_availability - ping the farm server and check if it's still unavailable");
        if (cb_ping_farm(cb, NULL, 0) != LDAP_SUCCESS) { /* farm still unavailable... Just change the timelimit */
            slapi_lock_mutex(cb->monitor_availability.lock_timeLimit);
            now = slapi_current_rel_time_t();
            cb->monitor_availability.unavailableTimeLimit = now + CB_UNAVAILABLE_PERIOD;
            slapi_unlock_mutex(cb->monitor_availability.lock_timeLimit);
            cb_send_ldap_result(pb, LDAP_OPERATIONS_ERROR, NULL, "FARM SERVER TEMPORARY UNAVAILABLE", 0, NULL);
            slapi_log_err(SLAPI_LOG_PLUGIN, CB_PLUGIN_SUBSYSTEM,
                          "cb_check_availability - Farm server still unavailable");
            return FARMSERVER_UNAVAILABLE;
        } else {
            /* farm is back !*/
            slapi_lock_mutex(cb->monitor_availability.lock_timeLimit);
            now = slapi_current_rel_time_t();
            cb->monitor_availability.unavailableTimeLimit = now; /* the unavailable period is finished */
            slapi_unlock_mutex(cb->monitor_availability.lock_timeLimit);
            /* The farmer server state backs to FARMSERVER_AVAILABLE, but this already done in cb_ping_farm, and also the reset of cpt*/
            return FARMSERVER_AVAILABLE;
        }
    }
    return FARMSERVER_AVAILABLE;
}
