]> git.sur5r.net Git - openldap/blobdiff - servers/slapd/back-ldap/chain.c
make referrals chasing optional (default is to chase them)
[openldap] / servers / slapd / back-ldap / chain.c
index b8659d93a76ad6462b895e9218ac058070f06ecb..7dcb95f29fc1d36a5c1c76e6fc8b8910d4f01bf1 100644 (file)
 #include "slap.h"
 #include "back-ldap.h"
 
-static BackendInfo *lback;
-
-#if 0
-static int
-ldap_chain_chk_referrals( Operation *op, SlapReply *rs )
-{
-       return LDAP_SUCCESS;
-}
-#endif
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+#define SLAP_CH_RESOLVE_SHIFT                          SLAP_CONTROL_SHIFT
+#define SLAP_CH_RESOLVE_MASK                           (0x3 << SLAP_CH_RESOLVE_SHIFT)
+#define SLAP_CH_RESOLVE_CHAINING_PREFERRED             (LDAP_CHAINING_PREFERRED << SLAP_CH_RESOLVE_SHIFT)
+#define SLAP_CH_RESOLVE_CHAINING_REQUIRED              (LDAP_CHAINING_REQUIRED << SLAP_CH_RESOLVE_SHIFT)
+#define SLAP_CH_RESOLVE_REFERRALS_PREFERRED            (LDAP_REFERRALS_PREFERRED << SLAP_CH_RESOLVE_SHIFT)
+#define SLAP_CH_RESOLVE_REFERRALS_REQUIRED             (LDAP_REFERRALS_REQUIRED << SLAP_CH_RESOLVE_SHIFT)
+#define SLAP_CH_RESOLVE_DEFAULT                                SLAP_CH_RESOLVE_CHAINING_PREFERRED
+#define        SLAP_CH_CONTINUATION_SHIFT                      (SLAP_CH_RESOLVE_SHIFT + 2)
+#define SLAP_CH_CONTINUATION_MASK                      (0x3 << SLAP_CH_CONTINUATION_SHIFT)
+#define SLAP_CH_CONTINUATION_CHAINING_PREFERRED                (LDAP_CHAINING_PREFERRED << SLAP_CH_CONTINUATION_SHIFT)
+#define SLAP_CH_CONTINUATION_CHAINING_REQUIRED         (LDAP_CHAINING_REQUIRED << SLAP_CH_CONTINUATION_SHIFT)
+#define SLAP_CH_CONTINUATION_REFERRALS_PREFERRED       (LDAP_REFERRALS_PREFERRED << SLAP_CH_CONTINUATION_SHIFT)
+#define SLAP_CH_CONTINUATION_REFERRALS_REQUIRED                (LDAP_REFERRALS_REQUIRED << SLAP_CH_CONTINUATION_SHIFT)
+#define SLAP_CH_CONTINUATION_DEFAULT                   SLAP_CH_CONTINUATION_CHAINING_PREFERRED
+
+#define o_chaining                     o_ctrlflag[sc_chainingBehavior]
+#define get_chaining(op)               ((op)->o_chaining & SLAP_CONTROL_MASK)
+#define get_chainingBehavior(op)       ((op)->o_chaining & (SLAP_CH_RESOLVE_MASK|SLAP_CH_CONTINUATION_MASK))
+#define get_resolveBehavior(op)                ((op)->o_chaining & SLAP_CH_RESOLVE_MASK)
+#define get_continuationBehavior(op)   ((op)->o_chaining & SLAP_CH_CONTINUATION_MASK)
+#endif /*  LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+#define        LDAP_CH_NONE                    ((void *)(0))
+#define        LDAP_CH_RES                     ((void *)(1))
+#define LDAP_CH_ERR                    ((void *)(2))
+
+static int             sc_chainingBehavior;
+static BackendInfo     *lback;
 
 static int
 ldap_chain_operational( Operation *op, SlapReply *rs )
 {
-       /* trap entries generated by back-ldap.
+       /* Trap entries generated by back-ldap.
+        * 
         * FIXME: we need a better way to recognize them; a cleaner
         * solution would be to be able to intercept the response
         * of be_operational(), so that we can divert only those
@@ -57,11 +78,19 @@ ldap_chain_operational( Operation *op, SlapReply *rs )
        return SLAP_CB_CONTINUE;
 }
 
+/*
+ * Search specific response that strips entryDN from entries
+ */
 static int
-ldap_chain_cb_response( Operation *op, SlapReply *rs )
+ldap_chain_cb_search_response( Operation *op, SlapReply *rs )
 {
        assert( op->o_tag == LDAP_REQ_SEARCH );
 
+       /* if in error, don't proceed any further */
+       if ( op->o_callback->sc_private == LDAP_CH_ERR ) {
+               return 0;
+       }
+
        if ( rs->sr_type == REP_SEARCH ) {
                Attribute       **ap = &rs->sr_entry->e_attrs;
 
@@ -82,127 +111,229 @@ ldap_chain_cb_response( Operation *op, SlapReply *rs )
                }
                
                return SLAP_CB_CONTINUE;
+
+       } else if ( rs->sr_type == REP_SEARCHREF ) {
+               /* if we get it here, it means the library was unable
+                * to chase the referral... */
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+               if ( get_chaining( op ) > SLAP_CONTROL_IGNORED ) {
+                       switch ( get_continuationBehavior( op ) ) {
+                       case SLAP_CH_RESOLVE_CHAINING_REQUIRED:
+                               op->o_callback->sc_private = LDAP_CH_ERR;
+                               return -1;
+
+                       default:
+                               break;
+                       }
+               }
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+               return SLAP_CB_CONTINUE;
+
+       } else if ( rs->sr_type == REP_RESULT ) {
+               /* back-ldap tried to send result */
+               op->o_callback->sc_private = LDAP_CH_RES;
        }
 
        return 0;
 }
 
+/*
+ * Dummy response that simply traces if back-ldap tried to send 
+ * anything to the client
+ */
+static int
+ldap_chain_cb_response( Operation *op, SlapReply *rs )
+{
+       /* if in error, don't proceed any further */
+       if ( op->o_callback->sc_private == LDAP_CH_ERR ) {
+               return 0;
+       }
+
+       if ( rs->sr_type == REP_RESULT ) {
+               op->o_callback->sc_private = LDAP_CH_RES;
+
+       } else if ( op->o_tag == LDAP_REQ_SEARCH && rs->sr_type == REP_SEARCH )
+       {
+               /* strip the entryDN attribute, but keep returning results */
+               (void)ldap_chain_cb_search_response( op, rs );
+       }
+
+       return SLAP_CB_CONTINUE;
+}
+
+static int
+ldap_chain_op(
+       Operation       *op,
+       SlapReply       *rs,
+       int             ( *op_f )( Operation *op, SlapReply *rs ), 
+       BerVarray       ref )
+{
+       slap_overinst   *on = (slap_overinst *) op->o_bd->bd_info;
+       struct ldapinfo li, *lip = (struct ldapinfo *)on->on_bi.bi_private;
+
+       /* NOTE: returned if ref is empty... */
+       int             rc = LDAP_OTHER;
+
+       if ( lip->url != NULL ) {
+               op->o_bd->be_private = on->on_bi.bi_private;
+               return ( *op_f )( op, rs );
+       }
+
+       li = *lip;
+       op->o_bd->be_private = &li;
+
+       /* if we parse the URI then by no means 
+        * we can cache stuff or reuse connections, 
+        * because in back-ldap there's no caching
+        * based on the URI value, which is supposed
+        * to be set once for all (correct?) */
+       op->o_do_not_cache = 1;
+
+       for ( ; !BER_BVISNULL( ref ); ref++ ) {
+               LDAPURLDesc     *srv;
+               char            *save_dn;
+                       
+               /* We're setting the URI of the first referral;
+                * what if there are more?
+
+Document: draft-ietf-ldapbis-protocol-27.txt
+
+4.1.10. Referral 
+   ...
+   If the client wishes to progress the operation, it MUST follow the 
+   referral by contacting one of the supported services. If multiple 
+   URIs are present, the client assumes that any supported URI may be 
+   used to progress the operation. 
+
+                * so we actually need to follow exactly one,
+                * and we can assume any is fine.
+                */
+       
+               /* parse reference and use 
+                * proto://[host][:port]/ only */
+               rc = ldap_url_parse_ext( ref->bv_val, &srv );
+               if ( rc != LDAP_URL_SUCCESS ) {
+                       /* try next */
+                       rc = LDAP_OTHER;
+                       continue;
+               }
+
+               /* remove DN essentially because later on 
+                * ldap_initialize() will parse the URL 
+                * as a comma-separated URL list */
+               save_dn = srv->lud_dn;
+               srv->lud_dn = "";
+               srv->lud_scope = LDAP_SCOPE_DEFAULT;
+               li.url = ldap_url_desc2str( srv );
+               srv->lud_dn = save_dn;
+               ldap_free_urldesc( srv );
+
+               if ( li.url == NULL ) {
+                       /* try next */
+                       rc = LDAP_OTHER;
+                       continue;
+               }
+
+               rc = ( *op_f )( op, rs );
+
+               ldap_memfree( li.url );
+               li.url = NULL;
+               
+               if ( rc == LDAP_SUCCESS && rs->sr_err == LDAP_SUCCESS ) {
+                       break;
+               }
+       }
+
+       return rc;
+}
+
 static int
 ldap_chain_response( Operation *op, SlapReply *rs )
 {
        slap_overinst   *on = (slap_overinst *) op->o_bd->bd_info;
        void            *private = op->o_bd->be_private;
-       slap_callback   *sc = op->o_callback;
-       LDAPControl     **prev = op->o_ctrls;
-       LDAPControl     **ctrls = NULL, *c[ 2 ], authz;
-       int             i, nctrls = 0, rc = 0;
+       slap_callback   *sc = op->o_callback,
+                       sc2 = { 0 };
+       int             rc = 0;
        int             cache = op->o_do_not_cache;
-       char            *authzid = NULL;
        BerVarray       ref;
        struct berval   ndn = op->o_ndn;
 
        struct ldapinfo li, *lip = (struct ldapinfo *)on->on_bi.bi_private;
 
-       if ( rs->sr_err != LDAP_REFERRAL && rs->sr_type != REP_SEARCHREF )
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       int             sr_err = rs->sr_err;
+       slap_reply_t    sr_type = rs->sr_type;
+       slap_mask_t     chain_mask = 0;
+       ber_len_t       chain_shift = 0;
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+       if ( rs->sr_err != LDAP_REFERRAL && rs->sr_type != REP_SEARCHREF ) {
                return SLAP_CB_CONTINUE;
+       }
 
-       ref = rs->sr_ref;
-       rs->sr_ref = NULL;
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       if ( rs->sr_err == LDAP_REFERRAL && get_chaining( op ) > SLAP_CONTROL_IGNORED ) {
+               switch ( get_resolveBehavior( op ) ) {
+               case SLAP_CH_RESOLVE_REFERRALS_PREFERRED:
+               case SLAP_CH_RESOLVE_REFERRALS_REQUIRED:
+                       return SLAP_CB_CONTINUE;
+
+               default:
+                       chain_mask = SLAP_CH_RESOLVE_MASK;
+                       chain_shift = SLAP_CH_RESOLVE_SHIFT;
+                       break;
+               }
 
-       op->o_callback = NULL;
-
-       if ( lip->url == NULL ) {
-               /* if we parse the URI then by no means 
-                * we can cache stuff or reuse connections, 
-                * because in back-ldap there's no caching
-                * based on the URI value, which is supposed
-                * to be set once for all (correct?) */
-               op->o_do_not_cache = 1;
-
-               /* FIXME: we're setting the URI of the first referral;
-                * what if there are more?  Is this something we should
-                * worry about? */
-               li = *lip;
-               op->o_bd->be_private = &li;
-
-               if ( rs->sr_type != REP_SEARCHREF ) {
-                       LDAPURLDesc     *srv;
-                       char            *save_dn;
-
-                       /* parse reference and use 
-                        * proto://[host][:port]/ only */
-                       rc = ldap_url_parse_ext( ref[0].bv_val, &srv );
-                       if ( rc != LDAP_URL_SUCCESS ) {
-                               /* error */
-                               return 1;
-                       }
+       } else if ( rs->sr_type == REP_SEARCHREF && get_chaining( op ) > SLAP_CONTROL_IGNORED ) {
+               switch ( get_continuationBehavior( op ) ) {
+               case SLAP_CH_CONTINUATION_REFERRALS_PREFERRED:
+               case SLAP_CH_CONTINUATION_REFERRALS_REQUIRED:
+                       return SLAP_CB_CONTINUE;
 
-                       /* remove DN essentially because later on 
-                        * ldap_initialize() will parse the URL 
-                        * as a comma-separated URL list */
-                       save_dn = srv->lud_dn;
-                       srv->lud_dn = "";
-                       srv->lud_scope = LDAP_SCOPE_DEFAULT;
-                       li.url = ldap_url_desc2str( srv );
-                       srv->lud_dn = save_dn;
-                       ldap_free_urldesc( srv );
-
-                       if ( li.url == NULL ) {
-                               /* error */
-                               return 1;
-                       }
+               default:
+                       chain_mask = SLAP_CH_CONTINUATION_MASK;
+                       chain_shift = SLAP_CH_CONTINUATION_SHIFT;
+                       break;
                }
-
-       } else {
-               op->o_bd->be_private = on->on_bi.bi_private;
        }
-
-       /* Chaining is performed by a privileged user on behalf
-        * of a normal user, using the ProxyAuthz control. However,
-        * Binds are done separately, on an anonymous session.
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+       /*
+        * TODO: add checks on who/when chain operations; e.g.:
+        *   a) what identities are authorized
+        *   b) what request DN (e.g. only chain requests rooted at <DN>)
+        *   c) what referral URIs
+        *   d) what protocol scheme (e.g. only ldaps://)
+        *   e) what ssf
         */
-       if ( op->o_tag != LDAP_REQ_BIND ) {
-               if ( prev ) {
-                       for ( i = 0; prev[i]; i++ )
-                               /* count and set prev to the last one */ ;
-                       nctrls = i;
-
-                       ctrls = op->o_tmpalloc((i + 1)*sizeof(LDAPControl *),
-                               op->o_tmpmemctx);
-                       for ( i = 0; i < nctrls; i++ ) {
-                               ctrls[i] = prev[i];
-                       }
 
-               } else {
-                       ctrls = c;
-               }
+       ref = rs->sr_ref;
+       rs->sr_ref = NULL;
 
-               ctrls[nctrls] = &authz;
-               ctrls[nctrls + 1] = NULL;
-               authz.ldctl_oid = LDAP_CONTROL_PROXY_AUTHZ;
-               authz.ldctl_iscritical = 1;
-               authz.ldctl_value = op->o_dn;
-               if ( !BER_BVISEMPTY( &op->o_dn ) ) {
-                       authzid = op->o_tmpalloc( op->o_dn.bv_len + STRLENOF("dn:"),
-                               op->o_tmpmemctx );
-                       strcpy(authzid, "dn:");
-                       strcpy(authzid + STRLENOF("dn:"), op->o_dn.bv_val);
-                       authz.ldctl_value.bv_len = op->o_dn.bv_len + STRLENOF("dn:");
-                       authz.ldctl_value.bv_val = authzid;
-               }
-               op->o_ctrls = ctrls;
-               op->o_ndn = op->o_bd->be_rootndn;
-       }
+       /* we need this to know if back-ldap returned any result */
+       sc2.sc_response = ldap_chain_cb_response;
+       op->o_callback = &sc2;
+
+       /* Chaining can be performed by a privileged user on behalf
+        * of normal users, using the ProxyAuthz control, by exploiting
+        * the identity assertion feature of back-ldap; see idassert-*
+        * directives in slapd-ldap(5).
+        *
+        * FIXME: the idassert-authcDN is one, will it be fine regardless
+        * of the URI we obtain from the referral?
+        */
 
        switch ( op->o_tag ) {
        case LDAP_REQ_BIND: {
                struct berval   rndn = op->o_req_ndn;
                Connection      *conn = op->o_conn;
 
+               /* FIXME: can we really get a referral for binds? */
                op->o_req_ndn = slap_empty_bv;
-
                op->o_conn = NULL;
-               rc = lback->bi_op_bind( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_bind, ref );
                op->o_req_ndn = rndn;
                op->o_conn = conn;
                }
@@ -215,7 +346,15 @@ ldap_chain_response( Operation *op, SlapReply *rs )
                        char            textbuf[ SLAP_TEXT_BUFLEN ];
                        size_t          textlen = sizeof( textbuf );
 
-                       /* global overlay; create entry */
+#if 0
+                       /* FIXME: op->o_bd is still set to the BackendDB 
+                        * structure of the database that tried to handle
+                        * the operation and actually returned a referral
+                        * ... */
+                       assert( SLAP_DBFLAGS( op->o_bd ) & SLAP_DBFLAG_GLOBAL_OVERLAY );
+#endif
+
+                       /* global overlay: create entry */
                        /* NOTE: this is a hack to use the chain overlay
                         * as global.  I expect to be able to remove this
                         * soon by using slap_mods2entry() earlier in
@@ -230,7 +369,7 @@ ldap_chain_response( Operation *op, SlapReply *rs )
                                break;
                        }
                }
-               rc = lback->bi_op_add( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_add, ref );
                if ( cleanup_attrs ) {
                        attrs_free( op->ora_e->e_attrs );
                        op->ora_e->e_attrs = NULL;
@@ -238,32 +377,38 @@ ldap_chain_response( Operation *op, SlapReply *rs )
                break;
                }
        case LDAP_REQ_DELETE:
-               rc = lback->bi_op_delete( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_delete, ref );
                break;
        case LDAP_REQ_MODRDN:
-               rc = lback->bi_op_modrdn( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_modrdn, ref );
                break;
        case LDAP_REQ_MODIFY:
-               rc = lback->bi_op_modify( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_modify, ref );
                break;
        case LDAP_REQ_COMPARE:
-               rc = lback->bi_op_compare( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_compare, ref );
                break;
        case LDAP_REQ_SEARCH:
                if ( rs->sr_type == REP_SEARCHREF ) {
                        struct berval   *curr = ref,
                                        odn = op->o_req_dn,
                                        ondn = op->o_req_ndn;
-                       slap_callback   sc2 = { 0 };
-                       int             tmprc = 0;
-                       ber_len_t       refcnt = 0;
-                       BerVarray       newref = NULL;
-
-                       sc2.sc_response = ldap_chain_cb_response;
-                       op->o_callback = &sc2;
 
                        rs->sr_type = REP_SEARCH;
 
+                       sc2.sc_response = ldap_chain_cb_search_response;
+
+                       li = *lip;
+                       li.url = NULL;
+                       op->o_bd->be_private = &li;
+                       
+                       /* if we parse the URI then by no means 
+                        * we can cache stuff or reuse connections, 
+                        * because in back-ldap there's no caching
+                        * based on the URI value, which is supposed
+                        * to be set once for all (correct?) */
+                       op->o_do_not_cache = 1;
+
                        /* copy the private info because we need to modify it */
                        for ( ; !BER_BVISNULL( &curr[0] ); curr++ ) {
                                LDAPURLDesc     *srv;
@@ -271,11 +416,11 @@ ldap_chain_response( Operation *op, SlapReply *rs )
 
                                /* parse reference and use
                                 * proto://[host][:port]/ only */
-                               tmprc = ldap_url_parse_ext( curr[0].bv_val, &srv );
-                               if ( tmprc != LDAP_URL_SUCCESS ) {
-                                       /* error */
-                                       rc = 1;
-                                       goto end_of_searchref;
+                               rc = ldap_url_parse_ext( curr[0].bv_val, &srv );
+                               if ( rc != LDAP_URL_SUCCESS ) {
+                                       /* try next */
+                                       rs->sr_err = LDAP_OTHER;
+                                       continue;
                                }
 
                                /* remove DN essentially because later on 
@@ -296,15 +441,15 @@ ldap_chain_response( Operation *op, SlapReply *rs )
                                ldap_free_urldesc( srv );
 
                                if ( li.url == NULL ) {
-                                       /* error */
-                                       rc = 1;
-                                       goto end_of_searchref;
+                                       /* try next */
+                                       rs->sr_err = LDAP_OTHER;
+                                       continue;
                                }
 
 
                                /* FIXME: should we also copy filter and scope?
                                 * according to RFC3296, no */
-                               tmprc = lback->bi_op_search( op, rs );
+                               rc = lback->bi_op_search( op, rs );
 
                                ldap_memfree( li.url );
                                li.url = NULL;
@@ -314,80 +459,79 @@ ldap_chain_response( Operation *op, SlapReply *rs )
                                op->o_tmpfree( op->o_req_ndn.bv_val,
                                                op->o_tmpmemctx );
 
-                               if ( tmprc ) {
-                                       /* error */
-                                       rc = 1;
-                                       goto end_of_searchref;
+                               if ( rc == LDAP_SUCCESS && rs->sr_err == LDAP_SUCCESS ) {
+                                       break;
                                }
 
-                               if ( rs->sr_err != LDAP_SUCCESS ) {
-                                       /* if search was not successful,
-                                        * at least return the referral! */
-                                       /* FIXME: assumes referrals 
-                                        * are always created via
-                                        * referral_rewrite() and freed via
-                                        * ber_bvarray_free( rs->sr_ref ) */
-                                       newref = ch_realloc( newref, sizeof( struct berval ) * (refcnt + 2) );
-                                       ber_dupbv( &newref[ refcnt ], &curr[ 0 ] );
-                                       refcnt++;
-                                       BER_BVZERO( &newref[ refcnt ] );
-                               }
+                               rc = rs->sr_err;
                        }
 
-end_of_searchref:;
                        op->o_req_dn = odn;
                        op->o_req_ndn = ondn;
                        rs->sr_type = REP_SEARCHREF;
                        rs->sr_entry = NULL;
 
-                       /* if the error was bad, it was already returned
-                        * by back-ldap; destroy the referrals left;
-                        * otherwise, let the frontend return them. */
-                       if ( newref ) {
-                               if ( rc == 0 ) {
-                                       rc = SLAP_CB_CONTINUE;
-                                       if ( ref != default_referral ) {
-                                               ber_bvarray_free( ref );
-                                       }
-                                       ref = newref;
-
-                               } else {
-                                       ber_bvarray_free( newref );
-                               }
+                       if ( rc != LDAP_SUCCESS ) {
+                               /* couldn't chase any of the referrals */
+                               rc = SLAP_CB_CONTINUE;
                        }
                        
                } else {
-                       rc = lback->bi_op_search( op, rs );
+                       rc = ldap_chain_op( op, rs, lback->bi_op_search, ref );
                }
                break;
        case LDAP_REQ_EXTENDED:
-               rc = lback->bi_extended( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_extended, ref );
                /* FIXME: ldap_back_extended() by design 
                 * doesn't send result; frontend is expected
                 * to send it... */
                if ( rc != SLAPD_ABANDON ) {
                        send_ldap_extended( op, rs );
+                       rc = LDAP_SUCCESS;
                }
                break;
        default:
                rc = SLAP_CB_CONTINUE;
                break;
        }
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       if ( rc != LDAP_SUCCESS || sc2.sc_private == LDAP_CH_ERR ) {
+               if ( rs->sr_err == LDAP_CANNOT_CHAIN ) {
+                       goto cannot_chain;
+               }
+
+               switch ( ( get_chainingBehavior( op ) & chain_mask ) >> chain_shift ) {
+               case LDAP_CHAINING_REQUIRED:
+cannot_chain:;
+                       op->o_callback = NULL;
+                       send_ldap_error( op, rs, LDAP_CANNOT_CHAIN, "operation cannot be completed without chaining" );
+                       break;
+
+               default:
+                       rc = SLAP_CB_CONTINUE;
+                       rs->sr_err = sr_err;
+                       rs->sr_type = sr_type;
+                       break;
+               }
+               goto dont_chain;
+       }
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+       if ( sc2.sc_private == LDAP_CH_NONE ) {
+               op->o_callback = NULL;
+               rc = rs->sr_err = slap_map_api2result( rs );
+               send_ldap_result( op, rs );
+       }
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+dont_chain:;
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
        op->o_do_not_cache = cache;
-       op->o_ctrls = prev;
        op->o_bd->be_private = private;
        op->o_callback = sc;
        op->o_ndn = ndn;
-       if ( ctrls && ctrls != c ) {
-               op->o_tmpfree( ctrls, op->o_tmpmemctx );
-       }
-       if ( authzid ) {
-               op->o_tmpfree( authzid, op->o_tmpmemctx );
-       }
        rs->sr_ref = ref;
-       if ( lip->url == NULL && li.url != NULL ) {
-               ldap_memfree( li.url );
-       }
 
        return rc;
 }
@@ -407,9 +551,9 @@ ldap_chain_db_config(
        int             rc;
 
        be->be_private = on->on_bi.bi_private;
-       if ( strncasecmp( argv[ 0 ], "chain-", sizeof( "chain-" ) - 1 ) == 0 ) {
+       if ( strncasecmp( argv[ 0 ], "chain-", STRLENOF( "chain-" ) ) == 0 ) {
                argv0 = argv[ 0 ];
-               argv[ 0 ] = &argv[ 0 ][ sizeof( "chain-" ) - 1 ];
+               argv[ 0 ] = &argv[ 0 ][ STRLENOF( "chain-" ) ];
        }
        rc = lback->bi_db_config( be, fname, lineno, argc, argv );
        if ( argv0 ) {
@@ -425,9 +569,9 @@ ldap_chain_db_init(
        BackendDB *be
 )
 {
-       slap_overinst *on = (slap_overinst *) be->bd_info;
-       void *private = be->be_private;
-       int rc;
+       slap_overinst   *on = (slap_overinst *)be->bd_info;
+       int             rc;
+       BackendDB       bd = *be;
 
        if ( lback == NULL ) {
                lback = backend_info( "ldap" );
@@ -437,14 +581,23 @@ ldap_chain_db_init(
                }
        }
 
-       be->be_private = NULL;
-       rc = lback->bi_db_init( be );
-       on->on_bi.bi_private = be->be_private;
-       be->be_private = private;
+       bd.be_private = NULL;
+       rc = lback->bi_db_init( &bd );
+       on->on_bi.bi_private = bd.be_private;
 
        return rc;
 }
 
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+static int
+ldap_chain_db_open(
+       BackendDB *be
+)
+{
+       return overlay_register_control( be, LDAP_CONTROL_X_CHAINING_BEHAVIOR );
+}
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
 static int
 ldap_chain_db_destroy(
        BackendDB *be
@@ -461,32 +614,190 @@ ldap_chain_db_destroy(
        return rc;
 }
 
+static int
+ldap_chain_connection_destroy(
+       BackendDB *be,
+       Connection *conn
+)
+{
+       slap_overinst *on = (slap_overinst *) be->bd_info;
+       void *private = be->be_private;
+       int rc;
+
+       be->be_private = on->on_bi.bi_private;
+       rc = lback->bi_connection_destroy( be, conn );
+       on->on_bi.bi_private = be->be_private;
+       be->be_private = private;
+       return rc;
+}
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+static int
+ldap_chain_parse_ctrl(
+       Operation       *op,
+       SlapReply       *rs,
+       LDAPControl     *ctrl )
+{
+       ber_tag_t       tag;
+       BerElement      *ber;
+       ber_int_t       mode,
+                       behavior;
+
+       if ( get_chaining( op ) != SLAP_CONTROL_NONE ) {
+               rs->sr_text = "Chaining behavior control specified multiple times";
+               return LDAP_PROTOCOL_ERROR;
+       }
+
+       if ( op->o_pagedresults != SLAP_CONTROL_NONE ) {
+               rs->sr_text = "Chaining behavior control specified with pagedResults control";
+               return LDAP_PROTOCOL_ERROR;
+       }
+
+       if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
+               mode = (SLAP_CH_RESOLVE_DEFAULT|SLAP_CH_CONTINUATION_DEFAULT);
+
+       } else {
+               ber_len_t       len;
+
+               /* Parse the control value
+                *      ChainingBehavior ::= SEQUENCE { 
+                *           resolveBehavior         Behavior OPTIONAL, 
+                *           continuationBehavior    Behavior OPTIONAL } 
+                *                             
+                *      Behavior :: = ENUMERATED { 
+                *           chainingPreferred       (0), 
+                *           chainingRequired        (1), 
+                *           referralsPreferred      (2), 
+                *           referralsRequired       (3) } 
+                */
+
+               ber = ber_init( &ctrl->ldctl_value );
+               if( ber == NULL ) {
+                       rs->sr_text = "internal error";
+                       return LDAP_OTHER;
+               }
+
+               tag = ber_scanf( ber, "{e" /* } */, &behavior );
+               /* FIXME: since the whole SEQUENCE is optional,
+                * should we accept no enumerations at all? */
+               if ( tag != LBER_ENUMERATED ) {
+                       rs->sr_text = "Chaining behavior control: resolveBehavior decoding error";
+                       return LDAP_PROTOCOL_ERROR;
+               }
+
+               switch ( behavior ) {
+               case LDAP_CHAINING_PREFERRED:
+                       mode = SLAP_CH_RESOLVE_CHAINING_PREFERRED;
+                       break;
+
+               case LDAP_CHAINING_REQUIRED:
+                       mode = SLAP_CH_RESOLVE_CHAINING_REQUIRED;
+                       break;
+
+               case LDAP_REFERRALS_PREFERRED:
+                       mode = SLAP_CH_RESOLVE_REFERRALS_PREFERRED;
+                       break;
+
+               case LDAP_REFERRALS_REQUIRED:
+                       mode = SLAP_CH_RESOLVE_REFERRALS_REQUIRED;
+                       break;
+
+               default:
+                       rs->sr_text = "Chaining behavior control: unknown resolveBehavior";
+                       return LDAP_PROTOCOL_ERROR;
+               }
+
+               tag = ber_peek_tag( ber, &len );
+               if ( tag == LBER_ENUMERATED ) {
+                       tag = ber_scanf( ber, "e", &behavior );
+                       if ( tag == LBER_ERROR ) {
+                               rs->sr_text = "Chaining behavior control: continuationBehavior decoding error";
+                               return LDAP_PROTOCOL_ERROR;
+                       }
+               }
+
+               if ( tag == LBER_DEFAULT ) {
+                       mode |= SLAP_CH_CONTINUATION_DEFAULT;
+
+               } else {
+                       switch ( behavior ) {
+                       case LDAP_CHAINING_PREFERRED:
+                               mode |= SLAP_CH_CONTINUATION_CHAINING_PREFERRED;
+                               break;
+
+                       case LDAP_CHAINING_REQUIRED:
+                               mode |= SLAP_CH_CONTINUATION_CHAINING_REQUIRED;
+                               break;
+
+                       case LDAP_REFERRALS_PREFERRED:
+                               mode |= SLAP_CH_CONTINUATION_REFERRALS_PREFERRED;
+                               break;
+
+                       case LDAP_REFERRALS_REQUIRED:
+                               mode |= SLAP_CH_CONTINUATION_REFERRALS_REQUIRED;
+                               break;
+
+                       default:
+                               rs->sr_text = "Chaining behavior control: unknown continuationBehavior";
+                               return LDAP_PROTOCOL_ERROR;
+                       }
+               }
+
+               if ( ( ber_scanf( ber, /* { */ "}") ) == LBER_ERROR ) {
+                       rs->sr_text = "Chaining behavior control: decoding error";
+                       return LDAP_PROTOCOL_ERROR;
+               }
+
+               (void) ber_free( ber, 1 );
+       }
+
+       op->o_chaining = mode | ( ctrl->ldctl_iscritical
+                       ? SLAP_CONTROL_CRITICAL
+                       : SLAP_CONTROL_NONCRITICAL );
+
+       return LDAP_SUCCESS;
+}
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
 static slap_overinst ldapchain;
 
 int
 chain_init( void )
 {
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       int     rc;
+
+       rc = register_supported_control( LDAP_CONTROL_X_CHAINING_BEHAVIOR,
+                       /* SLAP_CTRL_GLOBAL| */ SLAP_CTRL_ACCESS|SLAP_CTRL_HIDE, NULL,
+                       ldap_chain_parse_ctrl, &sc_chainingBehavior );
+       if ( rc != LDAP_SUCCESS ) {
+               fprintf( stderr, "Failed to register chaining behavior control: %d\n", rc );
+               return rc;
+       }
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
        ldapchain.on_bi.bi_type = "chain";
        ldapchain.on_bi.bi_db_init = ldap_chain_db_init;
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       ldapchain.on_bi.bi_db_open = ldap_chain_db_open;
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
        ldapchain.on_bi.bi_db_config = ldap_chain_db_config;
        ldapchain.on_bi.bi_db_destroy = ldap_chain_db_destroy;
-       
+
        /* ... otherwise the underlying backend's function would be called,
         * likely passing an invalid entry; on the contrary, the requested
         * operational attributes should have been returned while chasing
         * the referrals.  This all in all is a bit messy, because part
-        * of the operational attributes are generated by they backend;
+        * of the operational attributes are generated by the backend;
         * part by the frontend; back-ldap should receive all the available
-        * ones from the remote server, but then, on it own, it strips those
+        * ones from the remote server, but then, on its own, it strips those
         * it assumes will be (re)generated by the frontend (e.g.
         * subschemaSubentry.) */
        ldapchain.on_bi.bi_operational = ldap_chain_operational;
        
-       ldapchain.on_response = ldap_chain_response;
+       ldapchain.on_bi.bi_connection_destroy = ldap_chain_connection_destroy;
 
-#if 0
-       ldapchain.on_bi.bi_chk_referrals = ldap_chain_chk_referrals;
-#endif
+       ldapchain.on_response = ldap_chain_response;
 
        return overlay_register( &ldapchain );
 }