Adding upstream version 2.5.13+dfsg.upstream/2.5.13+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 736 insertions, 0 deletions

diff --git a/servers/lloadd/backend.c b/servers/lloadd/backend.c
new file mode 100644
index 0000000..ab0e932
--- /dev/null
+++ b/servers/lloadd/backend.c
@@ -0,0 +1,736 @@
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2022 The OpenLDAP Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+
+#include "portable.h"
+
+#include <ac/socket.h>
+#include <ac/errno.h>
+#include <ac/string.h>
+#include <ac/time.h>
+#include <ac/unistd.h>
+
+#include <event2/event.h>
+#include <event2/dns.h>
+
+#include "lutil.h"
+#include "lload.h"
+
+static void
+upstream_connect_cb( evutil_socket_t s, short what, void *arg )
+{
+    LloadPendingConnection *conn = arg;
+    LloadBackend *b = conn->backend;
+    int error = 0, rc = -1;
+    epoch_t epoch;
+
+    checked_lock( &b->b_mutex );
+    Debug( LDAP_DEBUG_CONNS, "upstream_connect_cb: "
+            "fd=%d connection callback for backend uri='%s'\n",
+            s, b->b_uri.bv_val );
+
+    if ( s != conn->fd ) {
+        /* backend_reset has been here first */
+        goto preempted;
+    }
+
+    epoch = epoch_join();
+
+    if ( what == EV_WRITE ) {
+        socklen_t optlen = sizeof(error);
+
+        if ( getsockopt( conn->fd, SOL_SOCKET, SO_ERROR, (void *)&error,
+                     &optlen ) < 0 ) {
+            goto done;
+        }
+        if ( error == EINTR || error == EINPROGRESS || error == EWOULDBLOCK ) {
+            checked_unlock( &b->b_mutex );
+            epoch_leave( epoch );
+            return;
+        } else if ( error ) {
+            goto done;
+        } else if ( upstream_init( s, conn->backend ) == NULL ) {
+            goto done;
+        }
+        rc = LDAP_SUCCESS;
+    }
+
+done:
+    epoch_leave( epoch );
+
+    LDAP_LIST_REMOVE( conn, next );
+    if ( rc ) {
+        evutil_closesocket( conn->fd );
+        b->b_opening--;
+        b->b_failed++;
+        if ( what & EV_TIMEOUT ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_connect_cb: "
+                    "fd=%d connection timed out\n",
+                    s );
+        } else {
+            char ebuf[128];
+            Debug( LDAP_DEBUG_ANY, "upstream_connect_cb: "
+                    "fd=%d connection set up failed%s%s\n",
+                    s, error ? ": " : "",
+                    error ? sock_errstr( error, ebuf, sizeof(ebuf) ) : "" );
+        }
+        backend_retry( b );
+    }
+preempted:
+    checked_unlock( &b->b_mutex );
+
+    event_free( conn->event );
+    ch_free( conn );
+}
+
+static void
+upstream_name_cb( int result, struct evutil_addrinfo *res, void *arg )
+{
+    LloadBackend *b = arg;
+    ber_socket_t s = AC_SOCKET_INVALID;
+    epoch_t epoch;
+    int rc;
+
+    if ( result == EVUTIL_EAI_CANCEL ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_name_cb: "
+                "cancelled\n" );
+        return;
+    }
+
+    checked_lock( &b->b_mutex );
+    /* We were already running when backend_reset tried to cancel us, but were
+     * already stuck waiting for the mutex, nothing to do and b_opening has
+     * been decremented as well */
+    if ( b->b_dns_req == NULL ) {
+        checked_unlock( &b->b_mutex );
+        return;
+    }
+    b->b_dns_req = NULL;
+
+    epoch = epoch_join();
+    if ( result || !res ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_name_cb: "
+                "name resolution failed for backend '%s': %s\n",
+                b->b_uri.bv_val, evutil_gai_strerror( result ) );
+        goto fail;
+    }
+
+    /* TODO: if we get failures, try the other addrinfos */
+    if ( (s = socket( res->ai_family, SOCK_STREAM, 0 )) ==
+            AC_SOCKET_INVALID ) {
+        goto fail;
+    }
+
+    if ( ber_pvt_socket_set_nonblock( s, 1 ) ) {
+        goto fail;
+    }
+
+#if defined(SO_KEEPALIVE) || defined(TCP_NODELAY)
+    if ( b->b_proto == LDAP_PROTO_TCP ) {
+        int dummy = 1;
+#ifdef SO_KEEPALIVE
+        if ( setsockopt( s, SOL_SOCKET, SO_KEEPALIVE, (char *)&dummy,
+                     sizeof(dummy) ) == AC_SOCKET_ERROR ) {
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "setsockopt(%d, SO_KEEPALIVE) failed (ignored).\n",
+                    s );
+        }
+        if ( bindconf.sb_keepalive.sk_idle > 0 ) {
+#ifdef TCP_KEEPIDLE
+            if ( setsockopt( s, IPPROTO_TCP, TCP_KEEPIDLE,
+                         (void *)&bindconf.sb_keepalive.sk_idle,
+                         sizeof(bindconf.sb_keepalive.sk_idle) ) ==
+                    AC_SOCKET_ERROR ) {
+                Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                        "setsockopt(%d, TCP_KEEPIDLE) failed (ignored).\n",
+                        s );
+            }
+#else
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "sockopt TCP_KEEPIDLE not supported on this system.\n" );
+#endif /* TCP_KEEPIDLE */
+        }
+        if ( bindconf.sb_keepalive.sk_probes > 0 ) {
+#ifdef TCP_KEEPCNT
+            if ( setsockopt( s, IPPROTO_TCP, TCP_KEEPCNT,
+                         (void *)&bindconf.sb_keepalive.sk_probes,
+                         sizeof(bindconf.sb_keepalive.sk_probes) ) ==
+                    AC_SOCKET_ERROR ) {
+                Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                        "setsockopt(%d, TCP_KEEPCNT) failed (ignored).\n",
+                        s );
+            }
+#else
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "sockopt TCP_KEEPCNT not supported on this system.\n" );
+#endif /* TCP_KEEPCNT */
+        }
+        if ( bindconf.sb_keepalive.sk_interval > 0 ) {
+#ifdef TCP_KEEPINTVL
+            if ( setsockopt( s, IPPROTO_TCP, TCP_KEEPINTVL,
+                         (void *)&bindconf.sb_keepalive.sk_interval,
+                         sizeof(bindconf.sb_keepalive.sk_interval) ) ==
+                    AC_SOCKET_ERROR ) {
+                Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                        "setsockopt(%d, TCP_KEEPINTVL) failed (ignored).\n",
+                        s );
+            }
+#else
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "sockopt TCP_KEEPINTVL not supported on this system.\n" );
+#endif /* TCP_KEEPINTVL */
+        }
+#endif /* SO_KEEPALIVE */
+        if ( bindconf.sb_tcp_user_timeout > 0 ) {
+#ifdef TCP_USER_TIMEOUT
+            if ( setsockopt( s, IPPROTO_TCP, TCP_USER_TIMEOUT,
+                         (void *)&bindconf.sb_tcp_user_timeout,
+                         sizeof(bindconf.sb_tcp_user_timeout) ) ==
+                    AC_SOCKET_ERROR ) {
+                Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                        "setsockopt(%d, TCP_USER_TIMEOUT) failed (ignored).\n",
+                        s );
+            }
+#else
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "sockopt TCP_USER_TIMEOUT not supported on this "
+                    "system.\n" );
+#endif /* TCP_USER_TIMEOUT */
+        }
+#ifdef TCP_NODELAY
+        if ( setsockopt( s, IPPROTO_TCP, TCP_NODELAY, (char *)&dummy,
+                     sizeof(dummy) ) == AC_SOCKET_ERROR ) {
+            Debug( LDAP_DEBUG_TRACE, "upstream_name_cb: "
+                    "setsockopt(%d, TCP_NODELAY) failed (ignored).\n",
+                    s );
+        }
+#endif /* TCP_NODELAY */
+    }
+#endif /* SO_KEEPALIVE || TCP_NODELAY */
+
+    if ( res->ai_family == PF_INET ) {
+        struct sockaddr_in *ai = (struct sockaddr_in *)res->ai_addr;
+        ai->sin_port = htons( b->b_port );
+        rc = connect( s, (struct sockaddr *)ai, res->ai_addrlen );
+    } else {
+        struct sockaddr_in6 *ai = (struct sockaddr_in6 *)res->ai_addr;
+        ai->sin6_port = htons( b->b_port );
+        rc = connect( s, (struct sockaddr *)ai, res->ai_addrlen );
+    }
+    /* Asynchronous connect */
+    if ( rc ) {
+        LloadPendingConnection *conn;
+
+        if ( errno != EINPROGRESS && errno != EWOULDBLOCK ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_name_cb: "
+                    "failed to connect to server '%s'\n",
+                    b->b_uri.bv_val );
+            evutil_closesocket( s );
+            goto fail;
+        }
+
+        conn = ch_calloc( 1, sizeof(LloadPendingConnection) );
+        LDAP_LIST_ENTRY_INIT( conn, next );
+        conn->backend = b;
+        conn->fd = s;
+
+        conn->event = event_new( lload_get_base( s ), s, EV_WRITE|EV_PERSIST,
+                upstream_connect_cb, conn );
+        if ( !conn->event ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_name_cb: "
+                    "failed to acquire an event to finish upstream "
+                    "connection setup.\n" );
+            ch_free( conn );
+            evutil_closesocket( s );
+            goto fail;
+        }
+
+        event_add( conn->event, lload_timeout_net );
+        LDAP_LIST_INSERT_HEAD( &b->b_connecting, conn, next );
+        Debug( LDAP_DEBUG_CONNS, "upstream_name_cb: "
+                "connection to backend uri=%s in progress\n",
+                b->b_uri.bv_val );
+    } else if ( upstream_init( s, b ) == NULL ) {
+        goto fail;
+    }
+
+    checked_unlock( &b->b_mutex );
+    evutil_freeaddrinfo( res );
+    epoch_leave( epoch );
+    return;
+
+fail:
+    if ( s != AC_SOCKET_INVALID ) {
+        evutil_closesocket( s );
+    }
+    b->b_opening--;
+    b->b_failed++;
+    backend_retry( b );
+    checked_unlock( &b->b_mutex );
+    if ( res ) {
+        evutil_freeaddrinfo( res );
+    }
+    epoch_leave( epoch );
+}
+
+LloadConnection *
+backend_select( LloadOperation *op, int *res )
+{
+    LloadBackend *b, *first, *next;
+
+    checked_lock( &backend_mutex );
+    first = b = current_backend;
+    checked_unlock( &backend_mutex );
+
+    *res = LDAP_UNAVAILABLE;
+
+    if ( !first ) {
+        return NULL;
+    }
+
+    /* TODO: Two runs, one with trylock, then one actually locked if we don't
+     * find anything? */
+    do {
+        lload_c_head *head;
+        LloadConnection *c;
+
+        checked_lock( &b->b_mutex );
+        next = LDAP_CIRCLEQ_LOOP_NEXT( &backend, b, b_next );
+
+        if ( b->b_max_pending && b->b_n_ops_executing >= b->b_max_pending ) {
+            Debug( LDAP_DEBUG_CONNS, "backend_select: "
+                    "backend %s too busy\n",
+                    b->b_uri.bv_val );
+            checked_unlock( &b->b_mutex );
+            b = next;
+            *res = LDAP_BUSY;
+            continue;
+        }
+
+        if ( op->o_tag == LDAP_REQ_BIND
+#ifdef LDAP_API_FEATURE_VERIFY_CREDENTIALS
+                && !(lload_features & LLOAD_FEATURE_VC)
+#endif /* LDAP_API_FEATURE_VERIFY_CREDENTIALS */
+        ) {
+            head = &b->b_bindconns;
+        } else {
+            head = &b->b_conns;
+        }
+        if ( !LDAP_CIRCLEQ_EMPTY( head ) ) {
+            *res = LDAP_BUSY;
+        }
+
+        LDAP_CIRCLEQ_FOREACH ( c, head, c_next ) {
+            checked_lock( &c->c_io_mutex );
+            CONNECTION_LOCK(c);
+            if ( c->c_state == LLOAD_C_READY && !c->c_pendingber &&
+                    ( b->b_max_conn_pending == 0 ||
+                            c->c_n_ops_executing < b->b_max_conn_pending ) ) {
+                Debug( LDAP_DEBUG_CONNS, "backend_select: "
+                        "selected connection connid=%lu for client "
+                        "connid=%lu msgid=%d\n",
+                        c->c_connid, op->o_client_connid, op->o_client_msgid );
+
+                /* c_state is DYING if we're about to be unlinked */
+                assert( IS_ALIVE( c, c_live ) );
+
+                /*
+                 * Round-robin step:
+                 * Rotate the queue to put this connection at the end, same for
+                 * the backend.
+                 */
+                LDAP_CIRCLEQ_MAKE_TAIL( head, c, c_next );
+
+                checked_lock( &backend_mutex );
+                current_backend = next;
+                checked_unlock( &backend_mutex );
+
+                b->b_n_ops_executing++;
+                if ( op->o_tag == LDAP_REQ_BIND ) {
+                    b->b_counters[LLOAD_STATS_OPS_BIND].lc_ops_received++;
+                } else {
+                    b->b_counters[LLOAD_STATS_OPS_OTHER].lc_ops_received++;
+                }
+                c->c_n_ops_executing++;
+                c->c_counters.lc_ops_received++;
+
+                checked_unlock( &b->b_mutex );
+                *res = LDAP_SUCCESS;
+                CONNECTION_ASSERT_LOCKED(c);
+                assert_locked( &c->c_io_mutex );
+                return c;
+            }
+            CONNECTION_UNLOCK(c);
+            checked_unlock( &c->c_io_mutex );
+        }
+        checked_unlock( &b->b_mutex );
+
+        b = next;
+    } while ( b != first );
+
+    return NULL;
+}
+
+/*
+ * Will schedule a connection attempt if there is a need for it. Need exclusive
+ * access to backend, its b_mutex is not touched here, though.
+ */
+void
+backend_retry( LloadBackend *b )
+{
+    int requested;
+
+    if ( slapd_shutdown ) {
+        Debug( LDAP_DEBUG_CONNS, "backend_retry: "
+                "shutting down\n" );
+        return;
+    }
+    assert_locked( &b->b_mutex );
+
+    requested = b->b_numconns;
+#ifdef LDAP_API_FEATURE_VERIFY_CREDENTIALS
+    if ( !(lload_features & LLOAD_FEATURE_VC) )
+#endif /* LDAP_API_FEATURE_VERIFY_CREDENTIALS */
+    {
+        requested += b->b_numbindconns;
+    }
+
+    if ( b->b_active + b->b_bindavail + b->b_opening >= requested ) {
+        Debug( LDAP_DEBUG_CONNS, "backend_retry: "
+                "no more connections needed for this backend\n" );
+        assert_locked( &b->b_mutex );
+        return;
+    }
+
+    if ( b->b_opening > 0 ) {
+        Debug( LDAP_DEBUG_CONNS, "backend_retry: "
+                "retry in progress already\n" );
+        assert( b->b_opening == 1 );
+        assert_locked( &b->b_mutex );
+        return;
+    }
+
+    /* We incremented b_opening when we activated the event, so it can't be
+     * pending */
+    assert( !event_pending( b->b_retry_event, EV_TIMEOUT, NULL ) );
+    b->b_opening++;
+
+    if ( b->b_failed > 0 ) {
+        Debug( LDAP_DEBUG_CONNS, "backend_retry: "
+                "scheduling a retry in %d ms\n",
+                b->b_retry_timeout );
+        event_add( b->b_retry_event, &b->b_retry_tv );
+        assert_locked( &b->b_mutex );
+        return;
+    }
+
+    Debug( LDAP_DEBUG_CONNS, "backend_retry: "
+            "scheduling re-connection straight away\n" );
+
+    if ( ldap_pvt_thread_pool_submit2(
+                 &connection_pool, backend_connect_task, b, &b->b_cookie ) ) {
+        Debug( LDAP_DEBUG_ANY, "backend_retry: "
+                "failed to submit retry task, scheduling a retry instead\n" );
+        /* The current implementation of ldap_pvt_thread_pool_submit2 can fail
+         * and still set (an invalid) cookie */
+        b->b_cookie = NULL;
+        b->b_failed++;
+        event_add( b->b_retry_event, &b->b_retry_tv );
+    }
+    assert_locked( &b->b_mutex );
+}
+
+void
+backend_connect( evutil_socket_t s, short what, void *arg )
+{
+    struct evutil_addrinfo hints = {};
+    LloadBackend *b = arg;
+    struct evdns_getaddrinfo_request *request, *placeholder;
+    char *hostname;
+    epoch_t epoch;
+
+    checked_lock( &b->b_mutex );
+    assert( b->b_dns_req == NULL );
+
+    if ( b->b_cookie ) {
+        b->b_cookie = NULL;
+    }
+
+    if ( slapd_shutdown ) {
+        Debug( LDAP_DEBUG_CONNS, "backend_connect: "
+                "doing nothing, shutdown in progress\n" );
+        b->b_opening--;
+        checked_unlock( &b->b_mutex );
+        return;
+    }
+
+    epoch = epoch_join();
+
+    Debug( LDAP_DEBUG_CONNS, "backend_connect: "
+            "%sattempting connection to %s\n",
+            (what & EV_TIMEOUT) ? "retry timeout finished, " : "",
+            b->b_host );
+
+#ifdef LDAP_PF_LOCAL
+    if ( b->b_proto == LDAP_PROTO_IPC ) {
+        struct sockaddr_un addr;
+        ber_socket_t s = socket( PF_LOCAL, SOCK_STREAM, 0 );
+        int rc;
+
+        if ( s == AC_SOCKET_INVALID ) {
+            goto fail;
+        }
+
+        rc = ber_pvt_socket_set_nonblock( s, 1 );
+        if ( rc ) {
+            evutil_closesocket( s );
+            goto fail;
+        }
+
+        if ( strlen( b->b_host ) > ( sizeof(addr.sun_path) - 1 ) ) {
+            evutil_closesocket( s );
+            goto fail;
+        }
+        memset( &addr, '\0', sizeof(addr) );
+        addr.sun_family = AF_LOCAL;
+        strcpy( addr.sun_path, b->b_host );
+
+        rc = connect(
+                s, (struct sockaddr *)&addr, sizeof(struct sockaddr_un) );
+        /* Asynchronous connect */
+        if ( rc ) {
+            LloadPendingConnection *conn;
+
+            if ( errno != EINPROGRESS && errno != EWOULDBLOCK ) {
+                evutil_closesocket( s );
+                goto fail;
+            }
+
+            conn = ch_calloc( 1, sizeof(LloadPendingConnection) );
+            LDAP_LIST_ENTRY_INIT( conn, next );
+            conn->backend = b;
+            conn->fd = s;
+
+            conn->event = event_new( lload_get_base( s ), s,
+                    EV_WRITE|EV_PERSIST, upstream_connect_cb, conn );
+            if ( !conn->event ) {
+                Debug( LDAP_DEBUG_ANY, "backend_connect: "
+                        "failed to acquire an event to finish upstream "
+                        "connection setup.\n" );
+                ch_free( conn );
+                evutil_closesocket( s );
+                goto fail;
+            }
+
+            event_add( conn->event, lload_timeout_net );
+            LDAP_LIST_INSERT_HEAD( &b->b_connecting, conn, next );
+            Debug( LDAP_DEBUG_CONNS, "backend_connect: "
+                    "connection to backend uri=%s in progress\n",
+                    b->b_uri.bv_val );
+        } else if ( upstream_init( s, b ) == NULL ) {
+            goto fail;
+        }
+
+        checked_unlock( &b->b_mutex );
+        epoch_leave( epoch );
+        return;
+    }
+#endif /* LDAP_PF_LOCAL */
+
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_flags = EVUTIL_AI_CANONNAME;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_protocol = IPPROTO_TCP;
+
+    hostname = b->b_host;
+
+    /*
+     * Picking any value on the stack. This is unique to our thread without
+     * having to call ldap_pvt_thread_self.
+     * We might have to revert to using ldap_pvt_thread_self eventually since
+     * this betrays where exactly our stack lies - potentially weakening some
+     * protections like ASLR.
+     */
+    placeholder = (struct evdns_getaddrinfo_request *)&request;
+    b->b_dns_req = placeholder;
+    checked_unlock( &b->b_mutex );
+
+    request = evdns_getaddrinfo(
+            dnsbase, hostname, NULL, &hints, upstream_name_cb, b );
+
+    checked_lock( &b->b_mutex );
+    assert( request || b->b_dns_req != placeholder );
+
+    /* Record the request, unless upstream_name_cb or another thread
+     * cleared it. Another thread is usually backend_reset or backend_connect
+     * if upstream_name_cb finished and scheduled another one */
+    if ( b->b_dns_req == placeholder ) {
+        b->b_dns_req = request;
+    }
+    checked_unlock( &b->b_mutex );
+    epoch_leave( epoch );
+    return;
+
+fail:
+    b->b_opening--;
+    b->b_failed++;
+    backend_retry( b );
+    checked_unlock( &b->b_mutex );
+    epoch_leave( epoch );
+}
+
+void *
+backend_connect_task( void *ctx, void *arg )
+{
+    backend_connect( -1, 0, arg );
+    return NULL;
+}
+
+/*
+ * Needs exclusive access to the backend and no other thread is allowed to call
+ * backend_retry while we're handling this.
+ *
+ * If gentle == 0, a full pause must be in effect, else we risk deadlocking on
+ * event_free().
+ */
+void
+backend_reset( LloadBackend *b, int gentle )
+{
+    assert_locked( &b->b_mutex );
+    if ( b->b_cookie ) {
+        if ( ldap_pvt_thread_pool_retract( b->b_cookie ) ) {
+            b->b_cookie = NULL;
+            b->b_opening--;
+        } else {
+            /*
+             * The task might not be cancelable because it just started
+             * executing.
+             *
+             * Shutdown should be the only time when the thread pool is
+             * in that state. Keep the cookie in to keep an eye on whether
+             * it's finished yet.
+             */
+            assert( slapd_shutdown );
+        }
+    }
+    /* Not safe to hold our mutex and call event_del/free if the event's
+     * callback is running, relinquish the mutex while we do so. */
+    if ( b->b_retry_event &&
+            event_pending( b->b_retry_event, EV_TIMEOUT, NULL ) ) {
+        assert( b->b_failed );
+        checked_unlock( &b->b_mutex );
+        event_del( b->b_retry_event );
+        checked_lock( &b->b_mutex );
+        b->b_opening--;
+    }
+    if ( b->b_dns_req ) {
+        evdns_getaddrinfo_cancel( b->b_dns_req );
+        b->b_dns_req = NULL;
+        b->b_opening--;
+    }
+    while ( !LDAP_LIST_EMPTY( &b->b_connecting ) ) {
+        LloadPendingConnection *pending = LDAP_LIST_FIRST( &b->b_connecting );
+
+        Debug( LDAP_DEBUG_CONNS, "backend_reset: "
+                "destroying socket pending connect() fd=%d\n",
+                pending->fd );
+
+        event_active( pending->event, EV_WRITE, 0 );
+        evutil_closesocket( pending->fd );
+        pending->fd = -1;
+        LDAP_LIST_REMOVE( pending, next );
+
+        if ( !gentle ) {
+            /* None of the event bases are running, we're safe to free the
+             * event right now and potentially free the backend itself */
+            event_free( pending->event );
+            ch_free( pending );
+        }
+        /* else, just let the event dispose of the resources on its own later */
+        b->b_opening--;
+    }
+    connections_walk(
+            &b->b_mutex, &b->b_preparing, lload_connection_close, &gentle );
+    assert( LDAP_CIRCLEQ_EMPTY( &b->b_preparing ) );
+    assert( b->b_opening == ( b->b_cookie ? 1 : 0 ) );
+    b->b_failed = 0;
+
+    connections_walk_last( &b->b_mutex, &b->b_bindconns, b->b_last_bindconn,
+            lload_connection_close, &gentle );
+    assert( gentle || b->b_bindavail == 0 );
+
+    connections_walk_last( &b->b_mutex, &b->b_conns, b->b_last_conn,
+            lload_connection_close, &gentle );
+    assert( gentle || b->b_active == 0 );
+    assert_locked( &b->b_mutex );
+}
+
+void
+lload_backend_destroy( LloadBackend *b )
+{
+    LloadBackend *next = LDAP_CIRCLEQ_LOOP_NEXT( &backend, b, b_next );
+
+    Debug( LDAP_DEBUG_CONNS, "lload_backend_destroy: "
+            "destroying backend uri='%s', numconns=%d, numbindconns=%d\n",
+            b->b_uri.bv_val, b->b_numconns, b->b_numbindconns );
+
+    checked_lock( &b->b_mutex );
+    b->b_numconns = b->b_numbindconns = 0;
+    backend_reset( b, 0 );
+
+    LDAP_CIRCLEQ_REMOVE( &backend, b, b_next );
+    if ( b == next ) {
+        current_backend = NULL;
+    } else {
+        current_backend = next;
+    }
+
+#ifdef BALANCER_MODULE
+    if ( b->b_monitor ) {
+        BackendDB *be;
+        struct berval monitordn = BER_BVC("cn=monitor");
+        int rc;
+
+        be = select_backend( &monitordn, 0 );
+
+        /* FIXME: implement proper subsys shutdown in back-monitor or make
+         * backend just an entry, not a subsys */
+        rc = b->b_monitor->mss_destroy( be, b->b_monitor );
+        assert( rc == LDAP_SUCCESS );
+    }
+#endif /* BALANCER_MODULE */
+    checked_unlock( &b->b_mutex );
+    ldap_pvt_thread_mutex_destroy( &b->b_mutex );
+
+    if ( b->b_retry_event ) {
+        event_del( b->b_retry_event );
+        event_free( b->b_retry_event );
+        b->b_retry_event = NULL;
+    }
+
+    ch_free( b->b_host );
+    ch_free( b->b_uri.bv_val );
+    ch_free( b->b_name.bv_val );
+    ch_free( b );
+}
+
+void
+lload_backends_destroy( void )
+{
+    while ( !LDAP_CIRCLEQ_EMPTY( &backend ) ) {
+        LloadBackend *b = LDAP_CIRCLEQ_FIRST( &backend );
+
+        lload_backend_destroy( b );
+    }
+}