]> git.sur5r.net Git - openldap/blobdiff - servers/slapd/back-ldap/chain.c
fix entry DN free
[openldap] / servers / slapd / back-ldap / chain.c
index f4bce3358607ddb977d98fe53719d04cdaeb6781..573ab84ebeb0be6a9caef20376c4acdb4e85d217 100644 (file)
@@ -2,7 +2,7 @@
 /* $OpenLDAP$ */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2003 The OpenLDAP Foundation.
+ * Copyright 2003-2005 The OpenLDAP Foundation.
  * Portions Copyright 2003 Howard Chu.
  * All rights reserved.
  *
 #include "slap.h"
 #include "back-ldap.h"
 
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+#define SLAP_CHAINING_DEFAULT                          LDAP_CHAINING_PREFERRED
+#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_CHAINING_DEFAULT << SLAP_CH_RESOLVE_SHIFT)
+#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_CHAINING_DEFAULT << SLAP_CH_CONTINUATION_SHIFT)
+
+#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)
+
+static int             sc_chainingBehavior;
+#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 BackendInfo     *lback;
+
+typedef struct ldap_chain_t {
+       struct ldapinfo         *lc_li;
+       unsigned                lc_flags;
+#define LDAP_CHAIN_F_NONE              0x00U
+#define        LDAP_CHAIN_F_CHAINING           0x01U
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       LDAPControl             lc_chaining_ctrl;
+       char                    lc_chaining_ctrlflag;
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+} ldap_chain_t;
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+static int
+chaining_control_add(
+               ldap_chain_t    *lc,
+               Operation       *op, 
+               LDAPControl     ***oldctrlsp )
+{
+       LDAPControl     **ctrls = NULL;
+       int             c = 0;
+
+       *oldctrlsp = op->o_ctrls;
+
+       /* default chaining control not defined */
+       if ( !( lc->lc_flags & LDAP_CHAIN_F_CHAINING ) ) {
+               return 0;
+       }
+
+       /* already present */
+       if ( get_chaining( op ) > SLAP_CONTROL_IGNORED ) {
+               return 0;
+       }
+
+       /* FIXME: check other incompatibilities */
+
+       /* add to other controls */
+       if ( op->o_ctrls ) {
+               for ( c = 0; op->o_ctrls[ c ]; c++ )
+                       /* count them */ ;
+       }
+
+       ctrls = ch_calloc( sizeof( LDAPControl *), c + 2 );
+       ctrls[ 0 ] = &lc->lc_chaining_ctrl;
+       if ( op->o_ctrls ) {
+               for ( c = 0; op->o_ctrls[ c ]; c++ ) {
+                       ctrls[ c + 1 ] = op->o_ctrls[ c ];
+               }
+       }
+       ctrls[ c + 1 ] = NULL;
+
+       op->o_ctrls = ctrls;
+
+       op->o_chaining = lc->lc_chaining_ctrlflag;
+
+       return 0;
+}
+
+static int
+chaining_control_remove(
+               Operation       *op, 
+               LDAPControl     ***oldctrlsp )
+{
+       LDAPControl     **oldctrls = *oldctrlsp;
+
+       /* we assume that the first control is the chaining control
+        * added by the chain overlay, so it's the only one we explicitly 
+        * free */
+       if ( op->o_ctrls != oldctrls ) {
+               assert( op->o_ctrls );
+               assert( op->o_ctrls[ 0 ] );
+
+               free( op->o_ctrls );
+
+               op->o_chaining = 0;
+               op->o_ctrls = oldctrls;
+       } 
+
+       *oldctrlsp = NULL;
+
+       return 0;
+}
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+static int
+ldap_chain_operational( Operation *op, SlapReply *rs )
+{
+       /* 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
+        * calls that fail because operational attributes were
+        * requested for entries that do not belong to the underlying
+        * database.  This fix is likely to intercept also entries
+        * generated by back-perl and so. */
+       if ( rs->sr_entry->e_private == NULL ) {
+               return 0;
+       }
+
+       return SLAP_CB_CONTINUE;
+}
+
+/*
+ * Search specific response that strips entryDN from entries
+ */
+static int
+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;
+
+               for ( ; *ap != NULL; ap = &(*ap)->a_next ) {
+                       /* will be generated later by frontend
+                        * (a cleaner solution would be that
+                        * the frontend checks if it already exists */
+                       if ( ad_cmp( (*ap)->a_desc, slap_schema.si_ad_entryDN ) == 0 )
+                       {
+                               Attribute *a = *ap;
+
+                               *ap = (*ap)->a_next;
+                               attr_free( a );
+
+                               /* there SHOULD be one only! */
+                               break;
+                       }
+               }
+               
+               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;
+       ldap_chain_t    *lc = (ldap_chain_t *)on->on_bi.bi_private;
+       struct ldapinfo li, *lip = lc->lc_li;
+
+       /* NOTE: returned if ref is empty... */
+       int             rc = LDAP_OTHER;
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       LDAPControl     **ctrls = NULL;
+       
+       (void)chaining_control_add( lc, op, &ctrls );
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+       if ( lip->url != NULL ) {
+               op->o_bd->be_private = lip;
+               rc = ( *op_f )( op, rs );
+               goto done;
+       }
+
+       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;
+               }
+       }
+
+done:;
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       (void)chaining_control_remove( op, &ctrls );
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+       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, authz;
-       int i, nctrls, rc;
-       int cache = op->o_do_not_cache;
-       char *authzid = NULL;
-       BerVarray ref;
-       struct berval ndn = op->o_ndn;
-
-       if ( rs->sr_err != LDAP_REFERRAL )
+       slap_overinst   *on = (slap_overinst *)op->o_bd->bd_info;
+       void            *private = op->o_bd->be_private;
+       slap_callback   *sc = op->o_callback,
+                       sc2 = { 0 };
+       int             rc = 0;
+       int             cache = op->o_do_not_cache;
+       BerVarray       ref;
+       struct berval   ndn = op->o_ndn;
+
+       ldap_chain_t    *lc = (ldap_chain_t *)on->on_bi.bi_private;
+       struct ldapinfo li, *lip = lc->lc_li;
+
+#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;
+       }
+
+#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;
+               }
+
+       } 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;
+
+               default:
+                       chain_mask = SLAP_CH_CONTINUATION_MASK;
+                       chain_shift = SLAP_CH_CONTINUATION_SHIFT;
+                       break;
+               }
+       }
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
 
-       /* currently we assume only one referral destination.
-        * we'll have to parse this in the future.
+       /*
+        * 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
         */
+
        ref = rs->sr_ref;
        rs->sr_ref = NULL;
 
-       op->o_bd->be_private = on->on_bi.bi_private;
-       op->o_callback = NULL;
+       /* we need this to know if back-ldap returned any result */
+       sc2.sc_response = ldap_chain_cb_response;
+       op->o_callback = &sc2;
 
-       /* 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.
+       /* 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?
         */
-       if ( op->o_tag != LDAP_REQ_BIND ) {
-               for (i=0; prev && prev[i]; i++);
-               nctrls = i;
-
-               /* Add an extra NULL slot */
-               if (!prev) i++;
-
-               ctrls = op->o_tmpalloc((i+1)*sizeof(LDAPControl *),
-                       op->o_tmpmemctx);
-               for (i=0; i <nctrls; i++)
-                       ctrls[i] = prev[i];
-               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 ( op->o_dn.bv_len ) {
-                       authzid = op->o_tmpalloc( op->o_dn.bv_len+4,
-                               op->o_tmpmemctx );
-                       strcpy(authzid, "dn: ");
-                       strcpy(authzid+4, op->o_dn.bv_val);
-                       authz.ldctl_value.bv_len = op->o_dn.bv_len + 4;
-                       authz.ldctl_value.bv_val = authzid;
-               }
-               op->o_ctrls = ctrls;
-               op->o_ndn = op->o_bd->be_rootndn;
-       }
-
-       switch( op->o_tag ) {
+
+       switch ( op->o_tag ) {
        case LDAP_REQ_BIND: {
-               struct berval rndn = op->o_req_ndn;
-               Connection *conn = op->o_conn;
+               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 = ldap_back_bind( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_bind, ref );
                op->o_req_ndn = rndn;
                op->o_conn = conn;
                }
                break;
        case LDAP_REQ_ADD:
-               rc = ldap_back_add( op, rs );
+               {
+               int             cleanup_attrs = 0;
+
+               if ( op->ora_e->e_attrs == NULL ) {
+                       char            textbuf[ SLAP_TEXT_BUFLEN ];
+                       size_t          textlen = sizeof( textbuf );
+
+#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
+                        * do_add(), adding the operational attrs later
+                        * if required. */
+                       rs->sr_err = slap_mods2entry( op->ora_modlist,
+                                       &op->ora_e, 0, 1,
+                                       &rs->sr_text, textbuf, textlen );
+                       if ( rs->sr_err != LDAP_SUCCESS ) {
+                               send_ldap_result( op, rs );
+                               rc = 1;
+                               break;
+                       }
+               }
+               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;
+               }
                break;
+               }
        case LDAP_REQ_DELETE:
-               rc = ldap_back_delete( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_delete, ref );
                break;
        case LDAP_REQ_MODRDN:
-               rc = ldap_back_modrdn( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_modrdn, ref );
                break;
        case LDAP_REQ_MODIFY:
-               rc = ldap_back_modify( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_modify, ref );
                break;
        case LDAP_REQ_COMPARE:
-               rc = ldap_back_compare( op, rs );
+               rc = ldap_chain_op( op, rs, lback->bi_op_compare, ref );
                break;
        case LDAP_REQ_SEARCH:
-               rc = ldap_back_search( op, rs );
+               if ( rs->sr_type == REP_SEARCHREF ) {
+                       struct berval   *curr = ref,
+                                       odn = op->o_req_dn,
+                                       ondn = op->o_req_ndn;
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+                       LDAPControl     **ctrls = NULL;
+       
+                       (void)chaining_control_add( lc, op, &ctrls );
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+                       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;
+                               char            *save_dn;
+
+                               /* parse reference and use
+                                * proto://[host][:port]/ only */
+                               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 
+                                * 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 );
+                               if ( li.url != NULL ) {
+                                       ber_str2bv_x( save_dn, 0, 1, &op->o_req_dn,
+                                                       op->o_tmpmemctx );
+                                       ber_dupbv_x( &op->o_req_ndn, &op->o_req_dn,
+                                                       op->o_tmpmemctx );
+                               }
+
+                               srv->lud_dn = save_dn;
+                               ldap_free_urldesc( srv );
+
+                               if ( li.url == NULL ) {
+                                       /* try next */
+                                       rs->sr_err = LDAP_OTHER;
+                                       continue;
+                               }
+
+
+                               /* FIXME: should we also copy filter and scope?
+                                * according to RFC3296, no */
+                               rc = lback->bi_op_search( op, rs );
+
+                               ldap_memfree( li.url );
+                               li.url = NULL;
+
+                               op->o_tmpfree( op->o_req_dn.bv_val,
+                                               op->o_tmpmemctx );
+                               op->o_tmpfree( op->o_req_ndn.bv_val,
+                                               op->o_tmpmemctx );
+
+                               if ( rc == LDAP_SUCCESS && rs->sr_err == LDAP_SUCCESS ) {
+                                       break;
+                               }
+
+                               rc = rs->sr_err;
+                       }
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+                       (void)chaining_control_remove( op, &ctrls );
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+                       op->o_req_dn = odn;
+                       op->o_req_ndn = ondn;
+                       rs->sr_type = REP_SEARCHREF;
+                       rs->sr_entry = NULL;
+
+                       if ( rc != LDAP_SUCCESS ) {
+                               /* couldn't chase any of the referrals */
+                               rc = SLAP_CB_CONTINUE;
+                       }
+                       
+               } else {
+                       rc = ldap_chain_op( op, rs, lback->bi_op_search, ref );
+               }
                break;
        case LDAP_REQ_EXTENDED:
-               rc = ldap_back_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 ) op->o_tmpfree( ctrls, op->o_tmpmemctx );
-       if ( authzid ) op->o_tmpfree( authzid, op->o_tmpmemctx );
        rs->sr_ref = ref;
 
        return rc;
 }
 
-static int ldap_chain_config(
-    BackendDB  *be,
-    const char *fname,
-    int                lineno,
-    int                argc,
-    char       **argv
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+static int
+ldap_chain_parse_ctrl(
+       Operation       *op,
+       SlapReply       *rs,
+       LDAPControl     *ctrl );
+
+static int
+str2chain( const char *s )
+{
+       if ( strcasecmp( s, "chainingPreferred" ) == 0 ) {
+               return LDAP_CHAINING_PREFERRED;
+               
+       } else if ( strcasecmp( s, "chainingRequired" ) == 0 ) {
+               return LDAP_CHAINING_REQUIRED;
+
+       } else if ( strcasecmp( s, "referralsPreferred" ) == 0 ) {
+               return LDAP_REFERRALS_PREFERRED;
+               
+       } else if ( strcasecmp( s, "referralsRequired" ) == 0 ) {
+               return LDAP_REFERRALS_REQUIRED;
+       }
+
+       return -1;
+}
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+
+static int
+ldap_chain_db_config(
+       BackendDB       *be,
+       const char      *fname,
+       int             lineno,
+       int             argc,
+       char    **argv
 )
 {
-       slap_overinst *on = (slap_overinst *) be->bd_info;
-       void *private = be->be_private;
-       int rc;
+       slap_overinst   *on = (slap_overinst *) be->bd_info;
+       ldap_chain_t    *lc = (ldap_chain_t *)on->on_bi.bi_private;
+       void            *private = be->be_private;
+       char            *argv0 = NULL;
+       int             rc;
+
+       if ( strncasecmp( argv[ 0 ], "chain-", STRLENOF( "chain-" ) ) == 0 ) {
+               argv0 = argv[ 0 ];
+               argv[ 0 ] = &argv[ 0 ][ STRLENOF( "chain-" ) ];
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+               if ( strcasecmp( argv[ 0 ], "chaining" ) == 0 ) {
+                       char                    **tmpargv = argv;
+                       BerElementBuffer        berbuf;
+                       BerElement              *ber = (BerElement *)&berbuf;
+                       int                     resolve = -1,
+                                               continuation = -1,
+                                               iscritical = 0;
+                       Operation               op = { 0 };
+                       SlapReply               rs = { 0 };
 
-       be->be_private = on->on_bi.bi_private;
-       rc = ldap_back_db_config( be, fname, lineno, argc, argv );
+                       lc->lc_chaining_ctrlflag = 0;
+
+                       for ( argc--, tmpargv++; argc > 0; argc--, tmpargv++ ) {
+                               if ( strncasecmp( tmpargv[ 0 ], "resolve=", STRLENOF( "resolve=" ) ) == 0 ) {
+                                       resolve = str2chain( tmpargv[ 0 ] + STRLENOF( "resolve=" ) );
+                                       if ( resolve == -1 ) {
+                                               fprintf( stderr, "%s line %d: "
+                                                       "illegal <resolve> value %s "
+                                                       "in \"chain-chaining>\"\n",
+                                                       fname, lineno, tmpargv[ 0 ] );
+                                               return 1;
+                                       }
+
+                               } else if ( strncasecmp( tmpargv[ 0 ], "continuation=", STRLENOF( "continuation=" ) ) == 0 ) {
+                                       continuation = str2chain( tmpargv[ 0 ] + STRLENOF( "continuation=" ) );
+                                       if ( continuation == -1 ) {
+                                               fprintf( stderr, "%s line %d: "
+                                                       "illegal <continuation> value %s "
+                                                       "in \"chain-chaining\"\n",
+                                                       fname, lineno, tmpargv[ 0 ] );
+                                               return 1;
+                                       }
+
+                               } else if ( strcasecmp( tmpargv[ 0 ], "critical" ) == 0 ) {
+                                       iscritical = 1;
+
+                               } else {
+                                       fprintf( stderr, "%s line %d: "
+                                               "unknown option in \"chain-chaining\"\n",
+                                               fname, lineno );
+                                       return 1;
+                               }
+                       }
+
+                       if ( resolve != -1 || continuation != -1 ) {
+                               int     err;
+
+                               if ( resolve == -1 ) {
+                                       /* default */
+                                       resolve = SLAP_CHAINING_DEFAULT;
+                               }
+
+                               ber_init2( ber, NULL, LBER_USE_DER );
+
+                               err = ber_printf( ber, "{e" /* } */, resolve );
+                               if ( err == -1 ) {
+                                       ber_free( ber, 1 );
+                                       fprintf( stderr, "%s line %d: "
+                                               "chaining behavior control encoding error!\n",
+                                               fname, lineno );
+                                       return 1;
+                               }
+
+                               if ( continuation > -1 ) {
+                                       err = ber_printf( ber, "e", continuation );
+                                       if ( err == -1 ) {
+                                               ber_free( ber, 1 );
+                                               fprintf( stderr, "%s line %d: "
+                                                       "chaining behavior control encoding error!\n",
+                                                       fname, lineno );
+                                               return 1;
+                                       }
+                               }
+
+                               err = ber_printf( ber, /* { */ "N}" );
+                               if ( err == -1 ) {
+                                       ber_free( ber, 1 );
+                                       fprintf( stderr, "%s line %d: "
+                                               "chaining behavior control encoding error!\n",
+                                               fname, lineno );
+                                       return 1;
+                               }
+
+                               if ( ber_flatten2( ber, &lc->lc_chaining_ctrl.ldctl_value, 0 ) == -1 ) {
+                                       exit( EXIT_FAILURE );
+                               }
+
+                       } else {
+                               BER_BVZERO( &lc->lc_chaining_ctrl.ldctl_value );
+                       }
+
+                       lc->lc_chaining_ctrl.ldctl_oid = LDAP_CONTROL_X_CHAINING_BEHAVIOR;
+                       lc->lc_chaining_ctrl.ldctl_iscritical = iscritical;
+
+                       if ( ldap_chain_parse_ctrl( &op, &rs, &lc->lc_chaining_ctrl ) != LDAP_SUCCESS )
+                       {
+                               fprintf( stderr, "%s line %d: "
+                                       "unable to parse chaining control%s%s\n",
+                                       fname, lineno,
+                                       rs.sr_text ? ": " : "",
+                                       rs.sr_text ? rs.sr_text : "" );
+                               return 1;
+                       }
+
+                       lc->lc_chaining_ctrlflag = op.o_chaining;
+
+                       lc->lc_flags |= LDAP_CHAIN_F_CHAINING;
+
+                       rc = 0;
+                       goto done;
+               }
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
+       }
+
+
+       be->be_private = lc->lc_li;
+       rc = lback->bi_db_config( be, fname, lineno, argc, argv );
        be->be_private = private;
+
+done:;
+       if ( argv0 ) {
+               argv[ 0 ] = argv0;
+       }
+
        return rc;
 }
 
-static int ldap_chain_init(
+static int
+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;
+       ldap_chain_t    *lc = NULL;
+       int             rc;
+       BackendDB       bd = *be;
+
+       if ( lback == NULL ) {
+               lback = backend_info( "ldap" );
+
+               if ( lback == NULL ) {
+                       return -1;
+               }
+       }
+
+       lc = ch_malloc( sizeof( ldap_chain_t ) );
+       memset( lc, 0, sizeof( ldap_chain_t ) );
+
+       bd.be_private = NULL;
+       rc = lback->bi_db_init( &bd );
+       lc->lc_li = (struct ldapinfo *)bd.be_private;
+       on->on_bi.bi_private = (void *)lc;
+
+       return rc;
+}
+
+static int
+ldap_chain_db_open(
+       BackendDB *be
+)
+{
+       int     rc = 0;
+
+#ifdef LDAP_CONTROL_X_CHAINING_BEHAVIOR
+       rc = overlay_register_control( be, LDAP_CONTROL_X_CHAINING_BEHAVIOR );
+#endif /* LDAP_CONTROL_X_CHAINING_BEHAVIOR */
 
-       be->be_private = NULL;
-       rc = ldap_back_db_init( be );
-       on->on_bi.bi_private = be->be_private;
-       be->be_private = private;
        return rc;
 }
 
-static int ldap_chain_destroy(
+static int
+ldap_chain_db_destroy(
        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;
+       ldap_chain_t    *lc = (ldap_chain_t *)on->on_bi.bi_private;
+       void            *private = be->be_private;
+       int             rc;
 
-       be->be_private = on->on_bi.bi_private;
-       rc = ldap_back_db_destroy( be );
-       on->on_bi.bi_private = be->be_private;
+       be->be_private = (void *)lc->lc_li;
+       rc = lback->bi_db_destroy( be );
+       lc->lc_li = be->be_private;
+       ch_free( lc );
+       on->on_bi.bi_private = NULL;
        be->be_private = private;
        return rc;
 }
 
+static int
+ldap_chain_connection_destroy(
+       BackendDB *be,
+       Connection *conn
+)
+{
+       slap_overinst   *on = (slap_overinst *) be->bd_info;
+       ldap_chain_t    *lc = (ldap_chain_t *)on->on_bi.bi_private;
+       void            *private = be->be_private;
+       int             rc;
+
+       be->be_private = (void *)lc->lc_li;
+       rc = lback->bi_connection_destroy( be, conn );
+       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 ldap_chain_setup()
+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_init;
-       ldapchain.on_bi.bi_db_config = ldap_chain_config;
-       ldapchain.on_bi.bi_db_destroy = ldap_chain_destroy;
+       ldapchain.on_bi.bi_db_init = ldap_chain_db_init;
+       ldapchain.on_bi.bi_db_open = ldap_chain_db_open;
+       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 the backend;
+        * part by the frontend; back-ldap should receive all the available
+        * 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_bi.bi_connection_destroy = ldap_chain_connection_destroy;
+
        ldapchain.on_response = ldap_chain_response;
 
        return overlay_register( &ldapchain );
 }
+