Adding upstream version 2.6.7+dfsg.upstream/2.6.7+dfsg

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

1 files changed, 1184 insertions, 0 deletions

diff --git a/servers/lloadd/upstream.c b/servers/lloadd/upstream.c
new file mode 100644
index 0000000..2784532
--- /dev/null
+++ b/servers/lloadd/upstream.c
@@ -0,0 +1,1184 @@
+/* $OpenLDAP$ */
+/* 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 "lload.h"
+
+#include "lutil.h"
+#include "lutil_ldap.h"
+
+#ifdef HAVE_CYRUS_SASL
+static const sasl_callback_t client_callbacks[] = {
+#ifdef SASL_CB_GETREALM
+        { SASL_CB_GETREALM, NULL, NULL },
+#endif
+        { SASL_CB_USER, NULL, NULL },
+        { SASL_CB_AUTHNAME, NULL, NULL },
+        { SASL_CB_PASS, NULL, NULL },
+        { SASL_CB_LIST_END, NULL, NULL }
+};
+#endif /* HAVE_CYRUS_SASL */
+
+static void upstream_unlink( LloadConnection *upstream );
+
+int
+lload_upstream_entry_cmp( const void *l, const void *r )
+{
+    return SLAP_PTRCMP( l, r );
+}
+
+static void
+linked_upstream_lost( LloadConnection *client )
+{
+    int gentle = 1;
+
+    CONNECTION_LOCK(client);
+    assert( client->c_restricted >= LLOAD_OP_RESTRICTED_UPSTREAM );
+    assert( client->c_linked_upstream );
+
+    client->c_restricted = LLOAD_OP_NOT_RESTRICTED;
+    client->c_linked_upstream = NULL;
+    CONNECTION_UNLOCK(client);
+    lload_connection_close( client, &gentle );
+}
+
+int
+forward_response( LloadConnection *client, LloadOperation *op, BerElement *ber )
+{
+    BerElement *output;
+    BerValue response, controls = BER_BVNULL;
+    ber_int_t msgid;
+    ber_tag_t tag, response_tag;
+    ber_len_t len;
+
+    CONNECTION_LOCK(client);
+    if ( op->o_client_msgid ) {
+        msgid = op->o_client_msgid;
+    } else {
+        assert( op->o_pin_id );
+        msgid = op->o_saved_msgid;
+        op->o_saved_msgid = 0;
+    }
+    CONNECTION_UNLOCK(client);
+
+    response_tag = ber_skip_element( ber, &response );
+
+    tag = ber_peek_tag( ber, &len );
+    if ( tag == LDAP_TAG_CONTROLS ) {
+        ber_skip_element( ber, &controls );
+    }
+
+    Debug( LDAP_DEBUG_TRACE, "forward_response: "
+            "%s to client connid=%lu request msgid=%d\n",
+            lload_msgtype2str( response_tag ), op->o_client_connid, msgid );
+
+    checked_lock( &client->c_io_mutex );
+    output = client->c_pendingber;
+    if ( output == NULL && (output = ber_alloc()) == NULL ) {
+        ber_free( ber, 1 );
+        checked_unlock( &client->c_io_mutex );
+        return -1;
+    }
+    client->c_pendingber = output;
+
+    ber_printf( output, "t{titOtO}", LDAP_TAG_MESSAGE,
+            LDAP_TAG_MSGID, msgid,
+            response_tag, &response,
+            LDAP_TAG_CONTROLS, BER_BV_OPTIONAL( &controls ) );
+
+    checked_unlock( &client->c_io_mutex );
+
+    ber_free( ber, 1 );
+    connection_write_cb( -1, 0, client );
+    return 0;
+}
+
+int
+forward_final_response(
+        LloadConnection *client,
+        LloadOperation *op,
+        BerElement *ber )
+{
+    int rc;
+
+    Debug( LDAP_DEBUG_STATS, "forward_final_response: "
+            "connid=%lu msgid=%d finishing up with a request for "
+            "client connid=%lu\n",
+            op->o_upstream_connid, op->o_upstream_msgid, op->o_client_connid );
+
+    rc = forward_response( client, op, ber );
+
+    op->o_res = LLOAD_OP_COMPLETED;
+    if ( !op->o_pin_id ) {
+        OPERATION_UNLINK(op);
+    }
+
+    return rc;
+}
+
+static int
+handle_unsolicited( LloadConnection *c, BerElement *ber )
+{
+    CONNECTION_ASSERT_LOCKED(c);
+
+    assert( c->c_state != LLOAD_C_INVALID );
+    if ( c->c_state == LLOAD_C_DYING ) {
+        CONNECTION_UNLOCK(c);
+        goto out;
+    }
+    c->c_state = LLOAD_C_CLOSING;
+
+    Debug( LDAP_DEBUG_STATS, "handle_unsolicited: "
+            "teardown for upstream connection connid=%lu\n",
+            c->c_connid );
+
+    CONNECTION_DESTROY(c);
+
+out:
+    ber_free( ber, 1 );
+    return -1;
+}
+
+/*
+ * Pull c->c_currentber from the connection and try to look up the operation on
+ * the upstream.
+ *
+ * If it's a notice of disconnection, we won't find it and need to tear down
+ * the connection and tell the clients, if we can't find the operation, ignore
+ * the message (either client already disconnected/abandoned it or the upstream
+ * is pulling our leg).
+ *
+ * Some responses need special handling:
+ * - Bind response
+ * - VC response where the client requested a Bind (both need to update the
+ *   client's bind status)
+ * - search entries/referrals and intermediate responses (will not trigger
+ *   operation to be removed)
+ *
+ * If the worker pool is overloaded, we might be called directly from
+ * the read callback, at that point, the connection hasn't been muted.
+ *
+ * TODO: when the client already has data pending on write, we should mute the
+ * upstream.
+ * - should record the BerElement on the Op and the Op on the client
+ *
+ * The following hold on entering any of the handlers:
+ * - op->o_upstream_refcnt > 0
+ * - op->o_upstream->c_refcnt > 0
+ * - op->o_client->c_refcnt > 0
+ */
+static int
+handle_one_response( LloadConnection *c )
+{
+    BerElement *ber;
+    LloadOperation *op = NULL, needle = { .o_upstream_connid = c->c_connid };
+    LloadOperationHandler handler = NULL;
+    ber_tag_t tag;
+    ber_len_t len;
+    int rc = LDAP_SUCCESS;
+
+    ber = c->c_currentber;
+    c->c_currentber = NULL;
+
+    tag = ber_get_int( ber, &needle.o_upstream_msgid );
+    if ( tag != LDAP_TAG_MSGID ) {
+        rc = -1;
+        ber_free( ber, 1 );
+        goto fail;
+    }
+
+    CONNECTION_LOCK(c);
+    if ( needle.o_upstream_msgid == 0 ) {
+        return handle_unsolicited( c, ber );
+    } else if ( !( op = ldap_tavl_find(
+                           c->c_ops, &needle, operation_upstream_cmp ) ) ) {
+        /* Already abandoned, do nothing */
+        CONNECTION_UNLOCK(c);
+        ber_free( ber, 1 );
+        return rc;
+        /*
+    } else if ( op->o_response_pending ) {
+        c->c_pendingop = op;
+        event_del( c->c_read_event );
+    */
+    } else {
+        CONNECTION_UNLOCK(c);
+        /*
+        op->o_response_pending = ber;
+        */
+
+        tag = ber_peek_tag( ber, &len );
+        switch ( tag ) {
+            case LDAP_RES_SEARCH_ENTRY:
+            case LDAP_RES_SEARCH_REFERENCE:
+            case LDAP_RES_INTERMEDIATE:
+                handler = forward_response;
+                break;
+            case LDAP_RES_BIND:
+                handler = handle_bind_response;
+                break;
+            case LDAP_RES_EXTENDED:
+                if ( op->o_tag == LDAP_REQ_BIND ) {
+#ifdef LDAP_API_FEATURE_VERIFY_CREDENTIALS
+                    if ( lload_features & LLOAD_FEATURE_VC ) {
+                        handler = handle_vc_bind_response;
+                    } else
+#endif /* LDAP_API_FEATURE_VERIFY_CREDENTIALS */
+                    {
+                        handler = handle_whoami_response;
+                    }
+                }
+                break;
+        }
+        if ( !handler ) {
+            handler = forward_final_response;
+        }
+    }
+    if ( op ) {
+        struct timeval tv, tvdiff;
+        uintptr_t diff;
+
+        gettimeofday( &tv, NULL );
+        if ( !timerisset( &op->o_last_response ) ) {
+            LloadBackend *b = c->c_backend;
+
+            timersub( &tv, &op->o_start, &tvdiff );
+            diff = 1000000 * tvdiff.tv_sec + tvdiff.tv_usec;
+
+            __atomic_add_fetch( &b->b_operation_count, 1, __ATOMIC_RELAXED );
+            __atomic_add_fetch( &b->b_operation_time, diff, __ATOMIC_RELAXED );
+        }
+        op->o_last_response = tv;
+
+        Debug( LDAP_DEBUG_STATS2, "handle_one_response: "
+                "upstream connid=%lu, processing response for "
+                "client connid=%lu, msgid=%d\n",
+                c->c_connid, op->o_client_connid, op->o_client_msgid );
+    } else {
+        tag = ber_peek_tag( ber, &len );
+        Debug( LDAP_DEBUG_STATS2, "handle_one_response: "
+                "upstream connid=%lu, %s, msgid=%d not for a pending "
+                "operation\n",
+                c->c_connid, lload_msgtype2str( tag ),
+                needle.o_upstream_msgid );
+    }
+
+    if ( handler ) {
+        LloadConnection *client;
+
+        checked_lock( &op->o_link_mutex );
+        client = op->o_client;
+        checked_unlock( &op->o_link_mutex );
+        if ( client && IS_ALIVE( client, c_live ) ) {
+            rc = handler( client, op, ber );
+        } else {
+            ber_free( ber, 1 );
+        }
+    } else {
+        assert(0);
+        ber_free( ber, 1 );
+    }
+
+fail:
+    if ( rc ) {
+        Debug( LDAP_DEBUG_STATS, "handle_one_response: "
+                "error on processing a response (%s) on upstream connection "
+                "connid=%ld, tag=%lx\n",
+                lload_msgtype2str( tag ), c->c_connid, tag );
+        CONNECTION_LOCK_DESTROY(c);
+    }
+    return rc;
+}
+
+#ifdef HAVE_CYRUS_SASL
+static int
+sasl_bind_step( LloadConnection *c, BerValue *scred, BerValue *ccred )
+{
+    LloadBackend *b = c->c_backend;
+    sasl_conn_t *ctx = c->c_sasl_authctx;
+    sasl_interact_t *prompts = NULL;
+    unsigned credlen;
+    int rc = -1;
+
+    if ( !ctx ) {
+        const char *mech = NULL;
+#ifdef HAVE_TLS
+        void *ssl;
+#endif /* HAVE_TLS */
+
+        if ( sasl_client_new( "ldap", b->b_host, NULL, NULL, client_callbacks,
+                     0, &ctx ) != SASL_OK ) {
+            goto done;
+        }
+        c->c_sasl_authctx = ctx;
+
+        assert( c->c_sasl_defaults == NULL );
+        c->c_sasl_defaults =
+                lutil_sasl_defaults( NULL, bindconf.sb_saslmech.bv_val,
+                        bindconf.sb_realm.bv_val, bindconf.sb_authcId.bv_val,
+                        bindconf.sb_cred.bv_val, bindconf.sb_authzId.bv_val );
+
+#ifdef HAVE_TLS
+        /* Check for TLS */
+        ssl = ldap_pvt_tls_sb_ctx( c->c_sb );
+        if ( ssl ) {
+            struct berval authid = BER_BVNULL;
+            ber_len_t ssf;
+
+            ssf = ldap_pvt_tls_get_strength( ssl );
+            (void)ldap_pvt_tls_get_my_dn( ssl, &authid, NULL, 0 );
+
+            sasl_setprop( ctx, SASL_SSF_EXTERNAL, &ssf );
+            sasl_setprop( ctx, SASL_AUTH_EXTERNAL, authid.bv_val );
+            ch_free( authid.bv_val );
+#ifdef SASL_CHANNEL_BINDING /* 2.1.25+ */
+            {
+                char cbinding[64];
+                struct berval cbv = { sizeof(cbinding), cbinding };
+                if ( ldap_pvt_tls_get_unique( ssl, &cbv, 0 ) ) {
+                    sasl_channel_binding_t *cb =
+                            ch_malloc( sizeof(*cb) + cbv.bv_len );
+                    void *cb_data;
+                    cb->name = "ldap";
+                    cb->critical = 0;
+                    cb->len = cbv.bv_len;
+                    cb->data = cb_data = cb + 1;
+                    memcpy( cb_data, cbv.bv_val, cbv.bv_len );
+                    sasl_setprop( ctx, SASL_CHANNEL_BINDING, cb );
+                    c->c_sasl_cbinding = cb;
+                }
+            }
+#endif
+        }
+#endif
+
+#if !defined(_WIN32)
+        /* Check for local */
+        if ( b->b_proto == LDAP_PROTO_IPC ) {
+            char authid[sizeof( "gidNumber=4294967295+uidNumber=4294967295,"
+                                "cn=peercred,cn=external,cn=auth" )];
+            int ssf = LDAP_PVT_SASL_LOCAL_SSF;
+
+            sprintf( authid,
+                    "gidNumber=%u+uidNumber=%u,"
+                    "cn=peercred,cn=external,cn=auth",
+                    getegid(), geteuid() );
+            sasl_setprop( ctx, SASL_SSF_EXTERNAL, &ssf );
+            sasl_setprop( ctx, SASL_AUTH_EXTERNAL, authid );
+        }
+#endif
+
+        do {
+            rc = sasl_client_start( ctx, bindconf.sb_saslmech.bv_val,
+                    &prompts,
+                    (const char **)&ccred->bv_val, &credlen,
+                    &mech );
+
+            if ( rc == SASL_INTERACT ) {
+                if ( lutil_sasl_interact( NULL, LDAP_SASL_QUIET,
+                             c->c_sasl_defaults, prompts ) ) {
+                    break;
+                }
+            }
+        } while ( rc == SASL_INTERACT );
+
+        ber_str2bv( mech, 0, 0, &c->c_sasl_bind_mech );
+    } else {
+        assert( c->c_sasl_defaults );
+
+        do {
+            rc = sasl_client_step( ctx,
+                    (scred == NULL) ? NULL : scred->bv_val,
+                    (scred == NULL) ? 0 : scred->bv_len,
+                    &prompts,
+                    (const char **)&ccred->bv_val, &credlen);
+
+            if ( rc == SASL_INTERACT ) {
+                if ( lutil_sasl_interact( NULL, LDAP_SASL_QUIET,
+                             c->c_sasl_defaults, prompts ) ) {
+                    break;
+                }
+            }
+        } while ( rc == SASL_INTERACT );
+    }
+
+    if ( rc == SASL_OK ) {
+        sasl_ssf_t *ssf;
+        rc = sasl_getprop( ctx, SASL_SSF, (const void **)(char *)&ssf );
+        if ( rc == SASL_OK && ssf && *ssf ) {
+            Debug( LDAP_DEBUG_CONNS, "sasl_bind_step: "
+                    "connid=%lu mech=%s setting up a new SASL security layer\n",
+                    c->c_connid, c->c_sasl_bind_mech.bv_val );
+            ldap_pvt_sasl_install( c->c_sb, ctx );
+        }
+    }
+    ccred->bv_len = credlen;
+
+done:
+    Debug( LDAP_DEBUG_TRACE, "sasl_bind_step: "
+            "connid=%lu next step for SASL bind mech=%s rc=%d\n",
+            c->c_connid, c->c_sasl_bind_mech.bv_val, rc );
+    return rc;
+}
+#endif /* HAVE_CYRUS_SASL */
+
+int
+upstream_bind_cb( LloadConnection *c )
+{
+    BerElement *ber = c->c_currentber;
+    LloadBackend *b = c->c_backend;
+    BerValue matcheddn, message;
+    ber_tag_t tag;
+    ber_int_t msgid, result;
+
+    c->c_currentber = NULL;
+
+    if ( ber_scanf( ber, "it", &msgid, &tag ) == LBER_ERROR ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_bind_cb: "
+                "protocol violation from server\n" );
+        goto fail;
+    }
+
+    if ( msgid != ( c->c_next_msgid - 1 ) || tag != LDAP_RES_BIND ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_bind_cb: "
+                "unexpected %s from server, msgid=%d\n",
+                lload_msgtype2str( tag ), msgid );
+        goto fail;
+    }
+
+    if ( ber_scanf( ber, "{emm" /* "}" */, &result, &matcheddn, &message ) ==
+                 LBER_ERROR ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_bind_cb: "
+                "response does not conform with a bind response\n" );
+        goto fail;
+    }
+
+    switch ( result ) {
+        case LDAP_SUCCESS:
+#ifdef HAVE_CYRUS_SASL
+        case LDAP_SASL_BIND_IN_PROGRESS:
+            if ( !BER_BVISNULL( &c->c_sasl_bind_mech ) ) {
+                BerValue scred = BER_BVNULL, ccred;
+                ber_len_t len;
+                int rc;
+
+                if ( ber_peek_tag( ber, &len ) == LDAP_TAG_SASL_RES_CREDS &&
+                        ber_scanf( ber, "m", &scred ) == LBER_ERROR ) {
+                    Debug( LDAP_DEBUG_ANY, "upstream_bind_cb: "
+                            "sasl bind response malformed\n" );
+                    goto fail;
+                }
+
+                rc = sasl_bind_step( c, &scred, &ccred );
+                if ( rc != SASL_OK &&
+                        ( rc != SASL_CONTINUE || result == LDAP_SUCCESS ) ) {
+                    goto fail;
+                }
+
+                if ( result == LDAP_SASL_BIND_IN_PROGRESS ) {
+                    BerElement *outber;
+
+                    checked_lock( &c->c_io_mutex );
+                    outber = c->c_pendingber;
+                    if ( outber == NULL && (outber = ber_alloc()) == NULL ) {
+                        checked_unlock( &c->c_io_mutex );
+                        goto fail;
+                    }
+                    c->c_pendingber = outber;
+
+                    msgid = c->c_next_msgid++;
+                    ber_printf( outber, "{it{iOt{OON}N}}",
+                            msgid, LDAP_REQ_BIND, LDAP_VERSION3,
+                            &bindconf.sb_binddn, LDAP_AUTH_SASL,
+                            &c->c_sasl_bind_mech, BER_BV_OPTIONAL( &ccred ) );
+                    checked_unlock( &c->c_io_mutex );
+
+                    connection_write_cb( -1, 0, c );
+
+                    if ( rc == SASL_OK ) {
+                        BER_BVZERO( &c->c_sasl_bind_mech );
+                    }
+                    break;
+                }
+            }
+            if ( result == LDAP_SASL_BIND_IN_PROGRESS ) {
+                goto fail;
+            }
+#endif /* HAVE_CYRUS_SASL */
+            CONNECTION_LOCK(c);
+            c->c_pdu_cb = handle_one_response;
+            c->c_state = LLOAD_C_READY;
+            c->c_type = LLOAD_C_OPEN;
+            c->c_read_timeout = NULL;
+            Debug( LDAP_DEBUG_CONNS, "upstream_bind_cb: "
+                    "connection connid=%lu for backend server '%s' is ready "
+                    "for use\n",
+                    c->c_connid, b->b_name.bv_val );
+            CONNECTION_UNLOCK(c);
+            checked_lock( &b->b_mutex );
+            LDAP_CIRCLEQ_REMOVE( &b->b_preparing, c, c_next );
+            b->b_active++;
+            b->b_opening--;
+            b->b_failed = 0;
+            if ( b->b_last_conn ) {
+                LDAP_CIRCLEQ_INSERT_AFTER(
+                        &b->b_conns, b->b_last_conn, c, c_next );
+            } else {
+                LDAP_CIRCLEQ_INSERT_HEAD( &b->b_conns, c, c_next );
+            }
+            b->b_last_conn = c;
+            backend_retry( b );
+            checked_unlock( &b->b_mutex );
+            break;
+        default:
+            Debug( LDAP_DEBUG_ANY, "upstream_bind_cb: "
+                    "upstream bind failed, rc=%d, message='%s'\n",
+                    result, message.bv_val );
+            goto fail;
+    }
+
+    checked_lock( &c->c_io_mutex );
+    c->c_io_state &= ~LLOAD_C_READ_HANDOVER;
+    checked_unlock( &c->c_io_mutex );
+    event_add( c->c_read_event, c->c_read_timeout );
+    ber_free( ber, 1 );
+    return -1;
+
+fail:
+    CONNECTION_LOCK_DESTROY(c);
+    ber_free( ber, 1 );
+    return -1;
+}
+
+void *
+upstream_bind( void *ctx, void *arg )
+{
+    LloadConnection *c = arg;
+    BerElement *ber;
+    ber_int_t msgid;
+
+    /* A reference was passed on to us */
+    assert( IS_ALIVE( c, c_refcnt ) );
+
+    if ( !IS_ALIVE( c, c_live ) ) {
+        RELEASE_REF( c, c_refcnt, c->c_destroy );
+        return NULL;
+    }
+
+    CONNECTION_LOCK(c);
+    assert( !event_pending( c->c_read_event, EV_READ, NULL ) );
+    c->c_pdu_cb = upstream_bind_cb;
+    CONNECTION_UNLOCK(c);
+
+    checked_lock( &c->c_io_mutex );
+    ber = c->c_pendingber;
+    if ( ber == NULL && (ber = ber_alloc()) == NULL ) {
+        goto fail;
+    }
+    c->c_pendingber = ber;
+    msgid = c->c_next_msgid++;
+
+    if ( bindconf.sb_method == LDAP_AUTH_SIMPLE ) {
+        /* simple bind */
+        ber_printf( ber, "{it{iOtON}}",
+                msgid, LDAP_REQ_BIND, LDAP_VERSION3,
+                &bindconf.sb_binddn, LDAP_AUTH_SIMPLE,
+                &bindconf.sb_cred );
+
+#ifdef HAVE_CYRUS_SASL
+    } else {
+        BerValue cred;
+        int rc;
+
+        rc = sasl_bind_step( c, NULL, &cred );
+        if ( rc != SASL_OK && rc != SASL_CONTINUE ) {
+            goto fail;
+        }
+
+        ber_printf( ber, "{it{iOt{OON}N}}",
+                msgid, LDAP_REQ_BIND, LDAP_VERSION3,
+                &bindconf.sb_binddn, LDAP_AUTH_SASL,
+                &c->c_sasl_bind_mech, BER_BV_OPTIONAL( &cred ) );
+
+        if ( rc == SASL_OK ) {
+            BER_BVZERO( &c->c_sasl_bind_mech );
+        }
+#endif /* HAVE_CYRUS_SASL */
+    }
+    /* TODO: can we be paused at this point? Then we'd have to move this line
+     * after connection_write_cb */
+    c->c_io_state &= ~LLOAD_C_READ_HANDOVER;
+    checked_unlock( &c->c_io_mutex );
+
+    connection_write_cb( -1, 0, c );
+
+    CONNECTION_LOCK(c);
+    c->c_read_timeout = lload_timeout_net;
+    event_add( c->c_read_event, c->c_read_timeout );
+    CONNECTION_UNLOCK(c);
+
+    RELEASE_REF( c, c_refcnt, c->c_destroy );
+    return NULL;
+
+fail:
+    checked_unlock( &c->c_io_mutex );
+    CONNECTION_LOCK_DESTROY(c);
+    RELEASE_REF( c, c_refcnt, c->c_destroy );
+    return NULL;
+}
+
+/*
+ * The backend is already locked when entering the function.
+ */
+static int
+upstream_finish( LloadConnection *c )
+{
+    LloadBackend *b = c->c_backend;
+    int is_bindconn = 0;
+
+    assert_locked( &b->b_mutex );
+    CONNECTION_ASSERT_LOCKED(c);
+    assert( c->c_live );
+    c->c_pdu_cb = handle_one_response;
+
+    /* Unless we are configured to use the VC exop, consider allocating the
+     * connection into the bind conn pool. Start off by allocating one for
+     * general use, then one for binds, then we start filling up the general
+     * connection pool, finally the bind pool */
+    if (
+#ifdef LDAP_API_FEATURE_VERIFY_CREDENTIALS
+            !(lload_features & LLOAD_FEATURE_VC) &&
+#endif /* LDAP_API_FEATURE_VERIFY_CREDENTIALS */
+            b->b_active && b->b_numbindconns ) {
+        if ( !b->b_bindavail ) {
+            is_bindconn = 1;
+        } else if ( b->b_active >= b->b_numconns &&
+                b->b_bindavail < b->b_numbindconns ) {
+            is_bindconn = 1;
+        }
+    }
+
+    if ( is_bindconn ) {
+        LDAP_CIRCLEQ_REMOVE( &b->b_preparing, c, c_next );
+        c->c_state = LLOAD_C_READY;
+        c->c_type = LLOAD_C_BIND;
+        b->b_bindavail++;
+        b->b_opening--;
+        b->b_failed = 0;
+        if ( b->b_last_bindconn ) {
+            LDAP_CIRCLEQ_INSERT_AFTER(
+                    &b->b_bindconns, b->b_last_bindconn, c, c_next );
+        } else {
+            LDAP_CIRCLEQ_INSERT_HEAD( &b->b_bindconns, c, c_next );
+        }
+        b->b_last_bindconn = c;
+    } else if ( bindconf.sb_method == LDAP_AUTH_NONE ) {
+        LDAP_CIRCLEQ_REMOVE( &b->b_preparing, c, c_next );
+        c->c_state = LLOAD_C_READY;
+        c->c_type = LLOAD_C_OPEN;
+        b->b_active++;
+        b->b_opening--;
+        b->b_failed = 0;
+        if ( b->b_last_conn ) {
+            LDAP_CIRCLEQ_INSERT_AFTER( &b->b_conns, b->b_last_conn, c, c_next );
+        } else {
+            LDAP_CIRCLEQ_INSERT_HEAD( &b->b_conns, c, c_next );
+        }
+        b->b_last_conn = c;
+    } else {
+        if ( ldap_pvt_thread_pool_submit(
+                     &connection_pool, upstream_bind, c ) ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_finish: "
+                    "failed to set up a bind callback for connid=%lu\n",
+                    c->c_connid );
+            return -1;
+        }
+        /* keep a reference for upstream_bind */
+        acquire_ref( &c->c_refcnt );
+
+        Debug( LDAP_DEBUG_CONNS, "upstream_finish: "
+                "scheduled a bind callback for connid=%lu\n",
+                c->c_connid );
+        return LDAP_SUCCESS;
+    }
+    event_add( c->c_read_event, c->c_read_timeout );
+
+    Debug( LDAP_DEBUG_CONNS, "upstream_finish: "
+            "%sconnection connid=%lu for backend server '%s' is ready for "
+            "use\n",
+            is_bindconn ? "bind " : "", c->c_connid, b->b_name.bv_val );
+
+    backend_retry( b );
+    return LDAP_SUCCESS;
+}
+
+#ifdef HAVE_TLS
+static void
+upstream_tls_handshake_cb( evutil_socket_t s, short what, void *arg )
+{
+    LloadConnection *c = arg;
+    LloadBackend *b;
+    epoch_t epoch;
+    int rc = LDAP_SUCCESS;
+
+    CONNECTION_LOCK(c);
+    if ( what & EV_TIMEOUT ) {
+        Debug( LDAP_DEBUG_CONNS, "upstream_tls_handshake_cb: "
+                "connid=%lu, timeout reached, destroying\n",
+                c->c_connid );
+        goto fail;
+    }
+    b = c->c_backend;
+
+    rc = ldap_pvt_tls_connect( lload_tls_backend_ld, c->c_sb, b->b_host );
+    if ( rc < 0 ) {
+        goto fail;
+    }
+
+    if ( rc == 0 ) {
+        struct event_base *base = event_get_base( c->c_read_event );
+
+        /*
+         * We're finished, replace the callbacks
+         *
+         * This is deadlock-safe, since both share the same base - the one
+         * that's just running us.
+         */
+        event_del( c->c_read_event );
+        event_del( c->c_write_event );
+
+        c->c_read_timeout = NULL;
+        event_assign( c->c_read_event, base, c->c_fd, EV_READ|EV_PERSIST,
+                connection_read_cb, c );
+        event_assign( c->c_write_event, base, c->c_fd, EV_WRITE,
+                connection_write_cb, c );
+        Debug( LDAP_DEBUG_CONNS, "upstream_tls_handshake_cb: "
+                "connid=%lu finished\n",
+                c->c_connid );
+        c->c_is_tls = LLOAD_TLS_ESTABLISHED;
+
+        CONNECTION_UNLOCK(c);
+        checked_lock( &b->b_mutex );
+        CONNECTION_LOCK(c);
+
+        rc = upstream_finish( c );
+        checked_unlock( &b->b_mutex );
+
+        if ( rc ) {
+            goto fail;
+        }
+    } else if ( ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_NEEDS_WRITE, NULL ) ) {
+        event_add( c->c_write_event, lload_write_timeout );
+        Debug( LDAP_DEBUG_CONNS, "upstream_tls_handshake_cb: "
+                "connid=%lu need write rc=%d\n",
+                c->c_connid, rc );
+    }
+    CONNECTION_UNLOCK(c);
+    return;
+
+fail:
+    Debug( LDAP_DEBUG_CONNS, "upstream_tls_handshake_cb: "
+            "connid=%lu failed rc=%d\n",
+            c->c_connid, rc );
+
+    assert( c->c_ops == NULL );
+    epoch = epoch_join();
+    CONNECTION_DESTROY(c);
+    epoch_leave( epoch );
+}
+
+static int
+upstream_starttls( LloadConnection *c )
+{
+    BerValue matcheddn, message, responseOid,
+             startTLSOid = BER_BVC(LDAP_EXOP_START_TLS);
+    BerElement *ber = c->c_currentber;
+    struct event_base *base;
+    ber_int_t msgid, result;
+    ber_tag_t tag;
+
+    c->c_currentber = NULL;
+    CONNECTION_LOCK(c);
+
+    if ( ber_scanf( ber, "it", &msgid, &tag ) == LBER_ERROR ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_starttls: "
+                "protocol violation from server\n" );
+        goto fail;
+    }
+
+    if ( msgid != ( c->c_next_msgid - 1 ) || tag != LDAP_RES_EXTENDED ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_starttls: "
+                "unexpected %s from server, msgid=%d\n",
+                lload_msgtype2str( tag ), msgid );
+        goto fail;
+    }
+
+    if ( ber_scanf( ber, "{emm}", &result, &matcheddn, &message ) ==
+                 LBER_ERROR ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_starttls: "
+                "protocol violation on StartTLS response\n" );
+        goto fail;
+    }
+
+    if ( (tag = ber_get_tag( ber )) != LBER_DEFAULT ) {
+        if ( tag != LDAP_TAG_EXOP_RES_OID ||
+                ber_scanf( ber, "{m}", &responseOid ) == LBER_DEFAULT ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_starttls: "
+                    "protocol violation on StartTLS response\n" );
+            goto fail;
+        }
+
+        if ( ber_bvcmp( &responseOid, &startTLSOid ) ) {
+            Debug( LDAP_DEBUG_ANY, "upstream_starttls: "
+                    "oid=%s not a StartTLS response\n",
+                    responseOid.bv_val );
+            goto fail;
+        }
+    }
+
+    if ( result != LDAP_SUCCESS ) {
+        LloadBackend *b = c->c_backend;
+        int rc;
+
+        Debug( LDAP_DEBUG_STATS, "upstream_starttls: "
+                "server doesn't support StartTLS rc=%d message='%s'%s\n",
+                result, message.bv_val,
+                (c->c_is_tls == LLOAD_STARTTLS_OPTIONAL) ? ", ignored" : "" );
+        if ( c->c_is_tls != LLOAD_STARTTLS_OPTIONAL ) {
+            goto fail;
+        }
+        c->c_is_tls = LLOAD_CLEARTEXT;
+
+        CONNECTION_UNLOCK(c);
+        checked_lock( &b->b_mutex );
+        CONNECTION_LOCK(c);
+
+        rc = upstream_finish( c );
+        checked_unlock( &b->b_mutex );
+
+        if ( rc ) {
+            goto fail;
+        }
+
+        ber_free( ber, 1 );
+        CONNECTION_UNLOCK(c);
+
+        checked_lock( &c->c_io_mutex );
+        c->c_io_state &= ~LLOAD_C_READ_HANDOVER;
+        checked_unlock( &c->c_io_mutex );
+
+        /* Do not keep handle_pdus running, we have adjusted c_read_event as we
+         * need it. */
+        return -1;
+    }
+
+    base = event_get_base( c->c_read_event );
+
+    c->c_io_state &= ~LLOAD_C_READ_HANDOVER;
+    event_del( c->c_read_event );
+    event_del( c->c_write_event );
+
+    c->c_read_timeout = lload_timeout_net;
+    event_assign( c->c_read_event, base, c->c_fd, EV_READ|EV_PERSIST,
+            upstream_tls_handshake_cb, c );
+    event_assign( c->c_write_event, base, c->c_fd, EV_WRITE,
+            upstream_tls_handshake_cb, c );
+
+    event_add( c->c_read_event, c->c_read_timeout );
+    event_add( c->c_write_event, lload_write_timeout );
+
+    CONNECTION_UNLOCK(c);
+
+    ber_free( ber, 1 );
+    return -1;
+
+fail:
+    ber_free( ber, 1 );
+    CONNECTION_DESTROY(c);
+    return -1;
+}
+#endif /* HAVE_TLS */
+
+/*
+ * We must already hold b->b_mutex when called.
+ */
+LloadConnection *
+upstream_init( ber_socket_t s, LloadBackend *b )
+{
+    LloadConnection *c;
+    struct event_base *base = lload_get_base( s );
+    struct event *event;
+    int flags;
+
+    assert( b != NULL );
+
+    flags = (b->b_proto == LDAP_PROTO_IPC) ? CONN_IS_IPC : 0;
+    if ( (c = lload_connection_init( s, b->b_host, flags )) == NULL ) {
+        return NULL;
+    }
+
+    CONNECTION_LOCK(c);
+    c->c_backend = b;
+#ifdef HAVE_TLS
+    c->c_is_tls = b->b_tls;
+#endif
+    c->c_pdu_cb = handle_one_response;
+
+    LDAP_CIRCLEQ_INSERT_HEAD( &b->b_preparing, c, c_next );
+    c->c_type = LLOAD_C_PREPARING;
+
+    {
+        ber_len_t max = sockbuf_max_incoming_upstream;
+        ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_MAX_INCOMING, &max );
+    }
+
+    event = event_new( base, s, EV_READ|EV_PERSIST, connection_read_cb, c );
+    if ( !event ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_init: "
+                "Read event could not be allocated\n" );
+        goto fail;
+    }
+    c->c_read_event = event;
+
+    event = event_new( base, s, EV_WRITE, connection_write_cb, c );
+    if ( !event ) {
+        Debug( LDAP_DEBUG_ANY, "upstream_init: "
+                "Write event could not be allocated\n" );
+        goto fail;
+    }
+    /* We only add the write event when we have data pending */
+    c->c_write_event = event;
+
+#ifdef BALANCER_MODULE
+    if ( b->b_monitor ) {
+        acquire_ref( &c->c_refcnt );
+        CONNECTION_UNLOCK(c);
+        checked_unlock( &b->b_mutex );
+        if ( lload_monitor_conn_entry_create( c, b->b_monitor ) ) {
+            RELEASE_REF( c, c_refcnt, c->c_destroy );
+            checked_lock( &b->b_mutex );
+            CONNECTION_LOCK(c);
+            goto fail;
+        }
+        checked_lock( &b->b_mutex );
+        CONNECTION_LOCK(c);
+        RELEASE_REF( c, c_refcnt, c->c_destroy );
+    }
+#endif /* BALANCER_MODULE */
+
+    c->c_destroy = upstream_destroy;
+    c->c_unlink = upstream_unlink;
+
+#ifdef HAVE_TLS
+    if ( c->c_is_tls == LLOAD_CLEARTEXT ) {
+#endif /* HAVE_TLS */
+        if ( upstream_finish( c ) ) {
+            goto fail;
+        }
+#ifdef HAVE_TLS
+    } else if ( c->c_is_tls == LLOAD_LDAPS ) {
+        event_assign( c->c_read_event, base, s, EV_READ|EV_PERSIST,
+                upstream_tls_handshake_cb, c );
+        event_add( c->c_read_event, c->c_read_timeout );
+        event_assign( c->c_write_event, base, s, EV_WRITE,
+                upstream_tls_handshake_cb, c );
+        event_add( c->c_write_event, lload_write_timeout );
+    } else if ( c->c_is_tls == LLOAD_STARTTLS ||
+            c->c_is_tls == LLOAD_STARTTLS_OPTIONAL ) {
+        BerElement *output;
+
+        checked_lock( &c->c_io_mutex );
+        if ( (output = c->c_pendingber = ber_alloc()) == NULL ) {
+            checked_unlock( &c->c_io_mutex );
+            goto fail;
+        }
+        ber_printf( output, "t{tit{ts}}", LDAP_TAG_MESSAGE,
+                LDAP_TAG_MSGID, c->c_next_msgid++,
+                LDAP_REQ_EXTENDED,
+                LDAP_TAG_EXOP_REQ_OID, LDAP_EXOP_START_TLS );
+        checked_unlock( &c->c_io_mutex );
+
+        c->c_pdu_cb = upstream_starttls;
+        CONNECTION_UNLOCK(c);
+        connection_write_cb( s, 0, c );
+        CONNECTION_LOCK(c);
+        if ( IS_ALIVE( c, c_live ) ) {
+            event_add( c->c_read_event, c->c_read_timeout );
+        }
+    }
+#endif /* HAVE_TLS */
+    CONNECTION_UNLOCK(c);
+
+    return c;
+
+fail:
+    if ( !IS_ALIVE( c, c_live ) ) {
+        /*
+         * Released while we were unlocked, it's scheduled for destruction
+         * already
+         */
+        return NULL;
+    }
+
+    if ( c->c_write_event ) {
+        event_del( c->c_write_event );
+        event_free( c->c_write_event );
+    }
+    if ( c->c_read_event ) {
+        event_del( c->c_read_event );
+        event_free( c->c_read_event );
+    }
+
+    c->c_state = LLOAD_C_INVALID;
+    c->c_live--;
+    c->c_refcnt--;
+    connection_destroy( c );
+
+    return NULL;
+}
+
+static void
+upstream_unlink( LloadConnection *c )
+{
+    LloadBackend *b = c->c_backend;
+    struct event *read_event, *write_event;
+    TAvlnode *root, *linked_root;
+    long freed, executing;
+
+    Debug( LDAP_DEBUG_CONNS, "upstream_unlink: "
+            "removing upstream connid=%lu\n",
+            c->c_connid );
+    CONNECTION_ASSERT_LOCKED(c);
+
+    assert( c->c_state != LLOAD_C_INVALID );
+    assert( c->c_state != LLOAD_C_DYING );
+
+    c->c_state = LLOAD_C_DYING;
+
+    read_event = c->c_read_event;
+    write_event = c->c_write_event;
+
+    root = c->c_ops;
+    c->c_ops = NULL;
+    executing = c->c_n_ops_executing;
+    c->c_n_ops_executing = 0;
+
+    linked_root = c->c_linked;
+    c->c_linked = NULL;
+
+    CONNECTION_UNLOCK(c);
+
+    freed = ldap_tavl_free( root, (AVL_FREE)operation_lost_upstream );
+    assert( freed == executing );
+
+    ldap_tavl_free( linked_root, (AVL_FREE)linked_upstream_lost );
+
+    /*
+     * Avoid a deadlock:
+     * event_del will block if the event is currently executing its callback,
+     * that callback might be waiting to lock c->c_mutex
+     */
+    if ( read_event ) {
+        event_del( read_event );
+    }
+
+    if ( write_event ) {
+        event_del( write_event );
+    }
+
+    checked_lock( &b->b_mutex );
+    if ( c->c_type == LLOAD_C_PREPARING ) {
+        LDAP_CIRCLEQ_REMOVE( &b->b_preparing, c, c_next );
+        b->b_opening--;
+        b->b_failed++;
+    } else if ( c->c_type == LLOAD_C_BIND ) {
+        if ( c == b->b_last_bindconn ) {
+            LloadConnection *prev =
+                    LDAP_CIRCLEQ_LOOP_PREV( &b->b_bindconns, c, c_next );
+            if ( prev == c ) {
+                b->b_last_bindconn = NULL;
+            } else {
+                b->b_last_bindconn = prev;
+            }
+        }
+        LDAP_CIRCLEQ_REMOVE( &b->b_bindconns, c, c_next );
+        b->b_bindavail--;
+    } else {
+        if ( c == b->b_last_conn ) {
+            LloadConnection *prev =
+                    LDAP_CIRCLEQ_LOOP_PREV( &b->b_conns, c, c_next );
+            if ( prev == c ) {
+                b->b_last_conn = NULL;
+            } else {
+                b->b_last_conn = prev;
+            }
+        }
+        LDAP_CIRCLEQ_REMOVE( &b->b_conns, c, c_next );
+        b->b_active--;
+    }
+    b->b_n_ops_executing -= executing;
+    backend_retry( b );
+    checked_unlock( &b->b_mutex );
+
+    CONNECTION_LOCK(c);
+    CONNECTION_ASSERT_LOCKED(c);
+}
+
+void
+upstream_destroy( LloadConnection *c )
+{
+    Debug( LDAP_DEBUG_CONNS, "upstream_destroy: "
+            "freeing connection connid=%lu\n",
+            c->c_connid );
+
+    CONNECTION_LOCK(c);
+    assert( c->c_state == LLOAD_C_DYING );
+
+#ifdef BALANCER_MODULE
+    /*
+     * Can't do this in upstream_unlink as that could be run from cn=monitor
+     * modify callback.
+     */
+    if ( !BER_BVISNULL( &c->c_monitor_dn ) ) {
+        lload_monitor_conn_unlink( c );
+    }
+#endif /* BALANCER_MODULE */
+
+    c->c_state = LLOAD_C_INVALID;
+
+    assert( c->c_ops == NULL );
+
+    if ( c->c_read_event ) {
+        event_free( c->c_read_event );
+        c->c_read_event = NULL;
+    }
+
+    if ( c->c_write_event ) {
+        event_free( c->c_write_event );
+        c->c_write_event = NULL;
+    }
+
+    if ( c->c_type != LLOAD_C_BIND ) {
+        BER_BVZERO( &c->c_sasl_bind_mech );
+    }
+    connection_destroy( c );
+}