util: rewrite dlinklist.h so that DLIST_ADD_END() is O(1)
[ira/wip.git] / source4 / dsdb / samdb / ldb_modules / repl_meta_data.c
index 249dd61a4a3e6c550ecf3d2e6592731ed9db4faa..67d7094d4c890e7c9bc8f8889b0b2b628c51727d 100644 (file)
 #include "lib/util/dlinklist.h"
 #include "dsdb/samdb/ldb_modules/util.h"
 #include "lib/util/binsearch.h"
+#include "libcli/security/security.h"
 
 #define W2K3_LINKED_ATTRIBUTES 1
 
 struct replmd_private {
        TALLOC_CTX *la_ctx;
        struct la_entry *la_list;
+       TALLOC_CTX *bl_ctx;
+       struct la_backlink *la_backlinks;
        struct nc_entry {
                struct nc_entry *prev, *next;
                struct ldb_dn *dn;
                uint64_t mod_usn;
+               uint64_t mod_usn_urgent;
        } *ncs;
 };
 
@@ -82,9 +86,67 @@ struct replmd_replicated_request {
        struct ldb_message *search_msg;
 
        uint64_t seq_num;
+       bool is_urgent;
+};
+
+enum urgent_situation {
+       REPL_URGENT_ON_CREATE = 1,
+       REPL_URGENT_ON_UPDATE = 3, /* activated on creating as well*/
+       REPL_URGENT_ON_DELETE = 4
+};
+
 
+static const struct {
+       const char *update_name;
+       enum urgent_situation repl_situation;
+} urgent_objects[] = {
+               {"nTDSDSA", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_DELETE)},
+               {"crossRef", (REPL_URGENT_ON_CREATE | REPL_URGENT_ON_DELETE)},
+               {"attributeSchema", REPL_URGENT_ON_UPDATE},
+               {"classSchema", REPL_URGENT_ON_UPDATE},
+               {"secret", REPL_URGENT_ON_UPDATE},
+               {"rIDManager", REPL_URGENT_ON_UPDATE},
+               {NULL, 0}
 };
 
+/* Attributes looked for when updating or deleting, to check for a urgent replication needed */
+static const char *urgent_attrs[] = {
+               "lockoutTime",
+               "pwdLastSet",
+               "userAccountControl",
+               NULL
+};
+
+
+static bool replmd_check_urgent_objectclass(const struct ldb_message_element *objectclass_el,
+                                       enum urgent_situation situation)
+{
+       int i, j;
+       for (i=0; urgent_objects[i].update_name; i++) {
+
+               if ((situation & urgent_objects[i].repl_situation) == 0) {
+                       continue;
+               }
+
+               for (j=0; j<objectclass_el->num_values; j++) {
+                       const struct ldb_val *v = &objectclass_el->values[j];
+                       if (ldb_attr_cmp((const char *)v->data, urgent_objects[i].update_name) == 0) {
+                               return true;
+                       }
+               }
+       }
+       return false;
+}
+
+static bool replmd_check_urgent_attribute(const struct ldb_message_element *el)
+{
+       if (ldb_attr_in_list(urgent_attrs, el->name)) {
+               return true;
+       }
+       return false;
+}
+
+
 static int replmd_replicated_apply_next(struct replmd_replicated_request *ar);
 
 /*
@@ -107,6 +169,176 @@ static int replmd_init(struct ldb_module *module)
        return ldb_next_init(module);
 }
 
+/*
+  cleanup our per-transaction contexts
+ */
+static void replmd_txn_cleanup(struct replmd_private *replmd_private)
+{
+       talloc_free(replmd_private->la_ctx);
+       replmd_private->la_list = NULL;
+       replmd_private->la_ctx = NULL;
+
+       talloc_free(replmd_private->bl_ctx);
+       replmd_private->la_backlinks = NULL;
+       replmd_private->bl_ctx = NULL;
+}
+
+
+struct la_backlink {
+       struct la_backlink *next, *prev;
+       const char *attr_name;
+       struct GUID forward_guid, target_guid;
+       bool active;
+};
+
+/*
+  process a backlinks we accumulated during a transaction, adding and
+  deleting the backlinks from the target objects
+ */
+static int replmd_process_backlink(struct ldb_module *module, struct la_backlink *bl)
+{
+       struct ldb_dn *target_dn, *source_dn;
+       int ret;
+       struct ldb_context *ldb = ldb_module_get_ctx(module);
+       struct ldb_message *msg;
+       TALLOC_CTX *tmp_ctx = talloc_new(bl);
+       char *dn_string;
+
+       /*
+         - find DN of target
+         - find DN of source
+         - construct ldb_message
+              - either an add or a delete
+        */
+       ret = dsdb_module_dn_by_guid(module, tmp_ctx, &bl->target_guid, &target_dn);
+       if (ret != LDB_SUCCESS) {
+               ldb_asprintf_errstring(ldb, "Failed to find target DN for linked attribute with GUID %s\n",
+                                      GUID_string(bl, &bl->target_guid));
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       ret = dsdb_module_dn_by_guid(module, tmp_ctx, &bl->forward_guid, &source_dn);
+       if (ret != LDB_SUCCESS) {
+               ldb_asprintf_errstring(ldb, "Failed to find source DN for linked attribute with GUID %s\n",
+                                      GUID_string(bl, &bl->forward_guid));
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       msg = ldb_msg_new(tmp_ctx);
+       if (msg == NULL) {
+               ldb_module_oom(module);
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       /* construct a ldb_message for adding/deleting the backlink */
+       msg->dn = target_dn;
+       dn_string = ldb_dn_get_extended_linearized(tmp_ctx, source_dn, 1);
+       if (!dn_string) {
+               ldb_module_oom(module);
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+       ret = ldb_msg_add_steal_string(msg, bl->attr_name, dn_string);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       msg->elements[0].flags = bl->active?LDB_FLAG_MOD_ADD:LDB_FLAG_MOD_DELETE;
+
+       ret = dsdb_module_modify(module, msg, 0);
+       if (ret != LDB_SUCCESS) {
+               ldb_asprintf_errstring(ldb, "Failed to %s backlink from %s to %s - %s",
+                                      bl->active?"add":"remove",
+                                      ldb_dn_get_linearized(source_dn),
+                                      ldb_dn_get_linearized(target_dn),
+                                      ldb_errstring(ldb));
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       talloc_free(tmp_ctx);
+       return ret;
+}
+
+/*
+  add a backlink to the list of backlinks to add/delete in the prepare
+  commit
+ */
+static int replmd_add_backlink(struct ldb_module *module, const struct dsdb_schema *schema,
+                              struct GUID *forward_guid, struct GUID *target_guid,
+                              bool active, const struct dsdb_attribute *schema_attr, bool immediate)
+{
+       const struct dsdb_attribute *target_attr;
+       struct la_backlink *bl;
+       struct replmd_private *replmd_private =
+               talloc_get_type_abort(ldb_module_get_private(module), struct replmd_private);
+
+       target_attr = dsdb_attribute_by_linkID(schema, schema_attr->linkID ^ 1);
+       if (!target_attr) {
+               /*
+                * windows 2003 has a broken schema where the
+                * definition of msDS-IsDomainFor is missing (which is
+                * supposed to be the backlink of the
+                * msDS-HasDomainNCs attribute
+                */
+               return LDB_SUCCESS;
+       }
+
+       /* see if its already in the list */
+       for (bl=replmd_private->la_backlinks; bl; bl=bl->next) {
+               if (GUID_equal(forward_guid, &bl->forward_guid) &&
+                   GUID_equal(target_guid, &bl->target_guid) &&
+                   (target_attr->lDAPDisplayName == bl->attr_name ||
+                    strcmp(target_attr->lDAPDisplayName, bl->attr_name) == 0)) {
+                       break;
+               }
+       }
+
+       if (bl) {
+               /* we found an existing one */
+               if (bl->active == active) {
+                       return LDB_SUCCESS;
+               }
+               DLIST_REMOVE(replmd_private->la_backlinks, bl);
+               talloc_free(bl);
+               return LDB_SUCCESS;
+       }
+
+       if (replmd_private->bl_ctx == NULL) {
+               replmd_private->bl_ctx = talloc_new(replmd_private);
+               if (replmd_private->bl_ctx == NULL) {
+                       ldb_module_oom(module);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+       }
+
+       /* its a new one */
+       bl = talloc(replmd_private->bl_ctx, struct la_backlink);
+       if (bl == NULL) {
+               ldb_module_oom(module);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       bl->attr_name = target_attr->lDAPDisplayName;
+       bl->forward_guid = *forward_guid;
+       bl->target_guid = *target_guid;
+       bl->active = active;
+
+       /* the caller may ask for this backlink to be processed
+          immediately */
+       if (immediate) {
+               int ret = replmd_process_backlink(module, bl);
+               talloc_free(bl);
+               return ret;
+       }
+
+       DLIST_ADD(replmd_private->la_backlinks, bl);
+
+       return LDB_SUCCESS;
+}
+
 
 /*
  * Callback for most write operations in this module:
@@ -145,6 +377,7 @@ static int replmd_op_callback(struct ldb_request *req, struct ldb_reply *ares)
        }
 
        if (!partition_ctrl) {
+               ldb_set_errstring(ldb_module_get_ctx(ac->module),"No partition control on reply");
                return ldb_module_done(ac->req, NULL,
                                       NULL, LDB_ERR_OPERATIONS_ERROR);
        }
@@ -178,6 +411,9 @@ static int replmd_op_callback(struct ldb_request *req, struct ldb_reply *ares)
 
                if (ac->seq_num > modified_partition->mod_usn) {
                        modified_partition->mod_usn = ac->seq_num;
+                       if (ac->is_urgent) {
+                               modified_partition->mod_usn_urgent = ac->seq_num;
+                       }
                }
        }
 
@@ -208,7 +444,7 @@ static int replmd_op_callback(struct ldb_request *req, struct ldb_reply *ares)
  */
 static int replmd_notify_store(struct ldb_module *module)
 {
-       struct replmd_private *replmd_private = 
+       struct replmd_private *replmd_private =
                talloc_get_type(ldb_module_get_private(module), struct replmd_private);
        struct ldb_context *ldb = ldb_module_get_ctx(module);
 
@@ -216,7 +452,9 @@ static int replmd_notify_store(struct ldb_module *module)
                int ret;
                struct nc_entry *modified_partition = replmd_private->ncs;
 
-               ret = dsdb_save_partition_usn(ldb, modified_partition->dn, modified_partition->mod_usn);
+               ret = dsdb_save_partition_usn(ldb, modified_partition->dn,
+                                               modified_partition->mod_usn,
+                                               modified_partition->mod_usn_urgent);
                if (ret != LDB_SUCCESS) {
                        DEBUG(0,(__location__ ": Failed to save partition uSN for %s\n",
                                 ldb_dn_get_linearized(modified_partition->dn)));
@@ -406,6 +644,73 @@ static void replmd_ldb_message_sort(struct ldb_message *msg,
                  discard_const_p(void, schema), (ldb_qsort_cmp_fn_t)replmd_ldb_message_element_attid_sort);
 }
 
+static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
+                              const struct GUID *invocation_id, uint64_t seq_num,
+                              uint64_t local_usn, NTTIME nttime, uint32_t version, bool deleted);
+
+
+/*
+  fix up linked attributes in replmd_add.
+  This involves setting up the right meta-data in extended DN
+  components, and creating backlinks to the object
+ */
+static int replmd_add_fix_la(struct ldb_module *module, struct ldb_message_element *el,
+                            uint64_t seq_num, const struct GUID *invocationId, time_t t,
+                            struct GUID *guid, const struct dsdb_attribute *sa)
+{
+       int i;
+       TALLOC_CTX *tmp_ctx = talloc_new(el->values);
+       struct ldb_context *ldb = ldb_module_get_ctx(module);
+       struct dsdb_schema *schema = dsdb_get_schema(ldb);
+       NTTIME now;
+
+       unix_to_nt_time(&now, t);
+
+       for (i=0; i<el->num_values; i++) {
+               struct ldb_val *v = &el->values[i];
+               struct dsdb_dn *dsdb_dn = dsdb_dn_parse(tmp_ctx, ldb, v, sa->syntax->ldap_oid);
+               struct GUID target_guid;
+               NTSTATUS status;
+               int ret;
+
+               /* note that the DN already has the extended
+                  components from the extended_dn_store module */
+               status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &target_guid, "GUID");
+               if (!NT_STATUS_IS_OK(status) || GUID_all_zero(&target_guid)) {
+                       ret = dsdb_module_guid_by_dn(module, dsdb_dn->dn, &target_guid);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return ret;
+                       }
+                       ret = dsdb_set_extended_dn_guid(dsdb_dn->dn, &target_guid, "GUID");
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return ret;
+                       }
+               }
+
+               ret = replmd_build_la_val(el->values, v, dsdb_dn, invocationId,
+                                         seq_num, seq_num, now, 0, false);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+
+               ret = replmd_add_backlink(module, schema, guid, &target_guid, true, sa, false);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+       }
+
+       talloc_free(tmp_ctx);
+       return LDB_SUCCESS;
+}
+
+
+/*
+  intercept add requests
+ */
 static int replmd_add(struct ldb_module *module, struct ldb_request *req)
 {
        struct ldb_context *ldb;
@@ -426,11 +731,13 @@ static int replmd_add(struct ldb_module *module, struct ldb_request *req)
        uint32_t i, ni=0;
        bool allow_add_guid = false;
        bool remove_current_guid = false;
+       bool is_urgent = false;
+       struct ldb_message_element *objectclass_el;
 
         /* check if there's a show relax control (used by provision to say 'I know what I'm doing') */
         control = ldb_request_get_control(req, LDB_CONTROL_RELAX_OID);
        if (control) {
-               allow_add_guid = 1;
+               allow_add_guid = true;
        }
 
        /* do not manipulate our control entries */
@@ -562,6 +869,19 @@ static int replmd_add(struct ldb_module *module, struct ldb_request *req)
                        continue;
                }
 
+#if W2K3_LINKED_ATTRIBUTES
+               if (sa->linkID != 0 && dsdb_functional_level(ldb) > DS_DOMAIN_FUNCTION_2000) {
+                       ret = replmd_add_fix_la(module, e, ac->seq_num, our_invocation_id, t, &guid, sa);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(ac);
+                               return ret;
+                       }
+                       /* linked attributes are not stored in
+                          replPropertyMetaData in FL above w2k */
+                       continue;
+               }
+#endif
+
                m->attid                        = sa->attributeID_id;
                m->version                      = 1;
                m->originating_change_time      = now;
@@ -633,11 +953,17 @@ static int replmd_add(struct ldb_module *module, struct ldb_request *req)
         */
        replmd_ldb_message_sort(msg, ac->schema);
 
+       objectclass_el = ldb_msg_find_element(msg, "objectClass");
+       is_urgent = replmd_check_urgent_objectclass(objectclass_el,
+                                                       REPL_URGENT_ON_CREATE);
+
+       ac->is_urgent = is_urgent;
        ret = ldb_build_add_req(&down_req, ldb, ac,
                                msg,
                                req->controls,
                                ac, replmd_op_callback,
                                req);
+
        if (ret != LDB_SUCCESS) {
                talloc_free(ac);
                return ret;
@@ -656,7 +982,7 @@ static int replmd_add(struct ldb_module *module, struct ldb_request *req)
 /*
  * update the replPropertyMetaData for one element
  */
-static int replmd_update_rpmd_element(struct ldb_context *ldb, 
+static int replmd_update_rpmd_element(struct ldb_context *ldb,
                                      struct ldb_message *msg,
                                      struct ldb_message_element *el,
                                      struct replPropertyMetaDataBlob *omd,
@@ -739,7 +1065,8 @@ static int replmd_update_rpmd_element(struct ldb_context *ldb,
 static int replmd_update_rpmd(struct ldb_module *module, 
                              const struct dsdb_schema *schema, 
                              struct ldb_message *msg, uint64_t *seq_num,
-                             time_t t)
+                             time_t t,
+                             bool *is_urgent)
 {
        const struct ldb_val *omd_value;
        enum ndr_err_code ndr_err;
@@ -748,9 +1075,10 @@ static int replmd_update_rpmd(struct ldb_module *module,
        NTTIME now;
        const struct GUID *our_invocation_id;
        int ret;
-       const char *attrs[] = { "replPropertyMetaData" , NULL };
+       const char *attrs[] = { "replPropertyMetaData" , "objectClass", NULL };
        struct ldb_result *res;
        struct ldb_context *ldb;
+       struct ldb_message_element *objectclass_el;
 
        ldb = ldb_module_get_ctx(module);
 
@@ -771,7 +1099,12 @@ static int replmd_update_rpmd(struct ldb_module *module,
                         ldb_dn_get_linearized(msg->dn)));
                return LDB_ERR_OPERATIONS_ERROR;
        }
-               
+
+       objectclass_el = ldb_msg_find_element(res->msgs[0], "objectClass");
+       if (is_urgent && replmd_check_urgent_objectclass(objectclass_el,
+                                                       REPL_URGENT_ON_UPDATE)) {
+               *is_urgent = true;
+       }
 
        omd_value = ldb_msg_find_ldb_val(res->msgs[0], "replPropertyMetaData");
        if (!omd_value) {
@@ -796,11 +1129,16 @@ static int replmd_update_rpmd(struct ldb_module *module,
        }
 
        for (i=0; i<msg->num_elements; i++) {
-               ret = replmd_update_rpmd_element(ldb, msg, &msg->elements[i], &omd, schema, seq_num, 
+               ret = replmd_update_rpmd_element(ldb, msg, &msg->elements[i], &omd, schema, seq_num,
                                                 our_invocation_id, now);
                if (ret != LDB_SUCCESS) {
                        return ret;
                }
+
+               if (is_urgent && !*is_urgent) {
+                       *is_urgent = replmd_check_urgent_attribute(&msg->elements[i]);
+               }
+
        }
 
        /*
@@ -846,7 +1184,6 @@ static int replmd_update_rpmd(struct ldb_module *module,
        return LDB_SUCCESS;     
 }
 
-
 struct parsed_dn {
        struct dsdb_dn *dsdb_dn;
        struct GUID *guid;
@@ -858,9 +1195,21 @@ static int parsed_dn_compare(struct parsed_dn *pdn1, struct parsed_dn *pdn2)
        return GUID_compare(pdn1->guid, pdn2->guid);
 }
 
-static struct parsed_dn *parsed_dn_find(struct parsed_dn *pdn, int count, struct GUID *guid)
+static struct parsed_dn *parsed_dn_find(struct parsed_dn *pdn, int count, struct GUID *guid, struct ldb_dn *dn)
 {
        struct parsed_dn *ret;
+       if (dn && GUID_all_zero(guid)) {
+               /* when updating a link using DRS, we sometimes get a
+                  NULL GUID. We then need to try and match by DN */
+               int i;
+               for (i=0; i<count; i++) {
+                       if (ldb_dn_compare(pdn[i].dsdb_dn->dn, dn) == 0) {
+                               dsdb_get_extended_dn_guid(pdn[i].dsdb_dn->dn, guid, "GUID");
+                               return &pdn[i];
+                       }
+               }
+               return NULL;
+       }
        BINARY_ARRAY_SEARCH(pdn, count, guid, guid, GUID_compare, ret);
        return ret;
 }
@@ -908,15 +1257,19 @@ static int get_parsed_dns(struct ldb_module *module, TALLOC_CTX *mem_ctx,
                        return LDB_ERR_OPERATIONS_ERROR;
                }
 
-               status = dsdb_get_extended_dn_guid(dn, p->guid);
+               status = dsdb_get_extended_dn_guid(dn, p->guid, "GUID");
                if (NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                        /* we got a DN without a GUID - go find the GUID */
-                       int ret = dsdb_find_guid_by_dn(ldb, dn, p->guid);
+                       int ret = dsdb_module_guid_by_dn(module, dn, p->guid);
                        if (ret != LDB_SUCCESS) {
                                ldb_asprintf_errstring(ldb, "Unable to find GUID for DN %s\n",
                                                       ldb_dn_get_linearized(dn));
                                return ret;
                        }
+                       ret = dsdb_set_extended_dn_guid(dn, p->guid, "GUID");
+                       if (ret != LDB_SUCCESS) {
+                               return ret;
+                       }
                } else if (!NT_STATUS_IS_OK(status)) {
                        return LDB_ERR_OPERATIONS_ERROR;
                }
@@ -933,29 +1286,31 @@ static int get_parsed_dns(struct ldb_module *module, TALLOC_CTX *mem_ctx,
 /*
   build a new extended DN, including all meta data fields
 
-  DELETED        = 1 or missing
-  RMD_ADDTIME    = originating_add_time
-  RMD_INVOCID    = originating_invocation_id
-  RMD_CHANGETIME = originating_change_time
-  RMD_USN        = originating_usn
-  RMD_VERSION    = version
+  RMD_FLAGS           = DSDB_RMD_FLAG_* bits
+  RMD_ADDTIME         = originating_add_time
+  RMD_INVOCID         = originating_invocation_id
+  RMD_CHANGETIME      = originating_change_time
+  RMD_ORIGINATING_USN = originating_usn
+  RMD_LOCAL_USN       = local_usn
+  RMD_VERSION         = version
  */
-static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct parsed_dn *p,
-                              const struct GUID *invocation_id, uint64_t seq_num, time_t t)
+static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
+                              const struct GUID *invocation_id, uint64_t seq_num,
+                              uint64_t local_usn, NTTIME nttime, uint32_t version, bool deleted)
 {
-       struct ldb_dn *dn = p->dsdb_dn->dn;
-       NTTIME now;
-       const char *tstring, *usn_string;
+       struct ldb_dn *dn = dsdb_dn->dn;
+       const char *tstring, *usn_string, *flags_string;
        struct ldb_val tval;
        struct ldb_val iid;
-       struct ldb_val usnv;
-       struct ldb_val vers;
+       struct ldb_val usnv, local_usnv;
+       struct ldb_val vers, flagsv;
        NTSTATUS status;
        int ret;
        const char *dnstring;
+       char *vstring;
+       uint32_t rmd_flags = deleted?DSDB_RMD_FLAG_DELETED:0;
 
-       unix_to_nt_time(&now, t);
-       tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)now);
+       tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)nttime);
        if (!tstring) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
@@ -967,14 +1322,30 @@ static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct pa
        }
        usnv = data_blob_string_const(usn_string);
 
-       vers = data_blob_string_const("0");
+       usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)local_usn);
+       if (!usn_string) {
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+       local_usnv = data_blob_string_const(usn_string);
+
+       vstring = talloc_asprintf(mem_ctx, "%lu", (unsigned long)version);
+       if (!vstring) {
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+       vers = data_blob_string_const(vstring);
 
        status = GUID_to_ndr_blob(invocation_id, dn, &iid);
        if (!NT_STATUS_IS_OK(status)) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = ldb_dn_set_extended_component(dn, "DELETED", NULL);
+       flags_string = talloc_asprintf(mem_ctx, "%u", rmd_flags);
+       if (!flags_string) {
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+       flagsv = data_blob_string_const(flags_string);
+
+       ret = ldb_dn_set_extended_component(dn, "RMD_FLAGS", &flagsv);
        if (ret != LDB_SUCCESS) return ret;
        ret = ldb_dn_set_extended_component(dn, "RMD_ADDTIME", &tval);
        if (ret != LDB_SUCCESS) return ret;
@@ -982,12 +1353,14 @@ static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct pa
        if (ret != LDB_SUCCESS) return ret;
        ret = ldb_dn_set_extended_component(dn, "RMD_CHANGETIME", &tval);
        if (ret != LDB_SUCCESS) return ret;
-       ret = ldb_dn_set_extended_component(dn, "RMD_USN", &usnv);
+       ret = ldb_dn_set_extended_component(dn, "RMD_LOCAL_USN", &local_usnv);
+       if (ret != LDB_SUCCESS) return ret;
+       ret = ldb_dn_set_extended_component(dn, "RMD_ORIGINATING_USN", &usnv);
        if (ret != LDB_SUCCESS) return ret;
        ret = ldb_dn_set_extended_component(dn, "RMD_VERSION", &vers);
        if (ret != LDB_SUCCESS) return ret;
 
-       dnstring = dsdb_dn_get_extended_linearized(mem_ctx, p->dsdb_dn, 1);
+       dnstring = dsdb_dn_get_extended_linearized(mem_ctx, dsdb_dn, 1);
        if (dnstring == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
@@ -996,30 +1369,62 @@ static int replmd_build_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct pa
        return LDB_SUCCESS;
 }
 
+static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
+                               struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
+                               uint64_t seq_num, uint64_t local_usn, NTTIME nttime,
+                               uint32_t version, bool deleted);
+
+/*
+  check if any links need upgrading from w2k format
+ */
+static int replmd_check_upgrade_links(struct parsed_dn *dns, uint32_t count, const struct GUID *invocation_id)
+{
+       int i;
+       for (i=0; i<count; i++) {
+               NTSTATUS status;
+               uint32_t version;
+               int ret;
+
+               status = dsdb_get_extended_dn_uint32(dns[i].dsdb_dn->dn, &version, "RMD_VERSION");
+               if (!NT_STATUS_EQUAL(status, NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
+                       continue;
+               }
+
+               /* it's an old one that needs upgrading */
+               ret = replmd_update_la_val(dns, dns[i].v, dns[i].dsdb_dn, dns[i].dsdb_dn, invocation_id,
+                                          1, 1, 0, 0, false);
+               if (ret != LDB_SUCCESS) {
+                       return ret;
+               }
+       }
+       return LDB_SUCCESS;
+}
 
 /*
   update an extended DN, including all meta data fields
 
   see replmd_build_la_val for value names
  */
-static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct parsed_dn *p,
-                               struct parsed_dn *old_p, const struct GUID *invocation_id,
-                               uint64_t seq_num, time_t t, bool deleted)
+static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct dsdb_dn *dsdb_dn,
+                               struct dsdb_dn *old_dsdb_dn, const struct GUID *invocation_id,
+                               uint64_t seq_num, uint64_t local_usn, NTTIME nttime,
+                               uint32_t version, bool deleted)
 {
-       struct ldb_dn *dn = p->dsdb_dn->dn;
-       NTTIME now;
-       const char *tstring, *usn_string;
+       struct ldb_dn *dn = dsdb_dn->dn;
+       const char *tstring, *usn_string, *flags_string;
        struct ldb_val tval;
        struct ldb_val iid;
-       struct ldb_val usnv;
-       struct ldb_val vers;
-       const struct ldb_val *old_addtime, *old_version;
+       struct ldb_val usnv, local_usnv;
+       struct ldb_val vers, flagsv;
+       const struct ldb_val *old_addtime;
+       uint32_t old_version;
        NTSTATUS status;
        int ret;
        const char *dnstring;
+       char *vstring;
+       uint32_t rmd_flags = deleted?DSDB_RMD_FLAG_DELETED:0;
 
-       unix_to_nt_time(&now, t);
-       tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)now);
+       tstring = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)nttime);
        if (!tstring) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
@@ -1031,26 +1436,32 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct p
        }
        usnv = data_blob_string_const(usn_string);
 
+       usn_string = talloc_asprintf(mem_ctx, "%llu", (unsigned long long)local_usn);
+       if (!usn_string) {
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+       local_usnv = data_blob_string_const(usn_string);
+
        status = GUID_to_ndr_blob(invocation_id, dn, &iid);
        if (!NT_STATUS_IS_OK(status)) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       if (deleted) {
-               struct ldb_val dv;
-               dv = data_blob_string_const("1");
-               ret = ldb_dn_set_extended_component(dn, "DELETED", &dv);
-       } else {
-               ret = ldb_dn_set_extended_component(dn, "DELETED", NULL);
+       flags_string = talloc_asprintf(mem_ctx, "%u", rmd_flags);
+       if (!flags_string) {
+               return LDB_ERR_OPERATIONS_ERROR;
        }
+       flagsv = data_blob_string_const(flags_string);
+
+       ret = ldb_dn_set_extended_component(dn, "RMD_FLAGS", &flagsv);
        if (ret != LDB_SUCCESS) return ret;
 
        /* get the ADDTIME from the original */
-       old_addtime = ldb_dn_get_extended_component(old_p->dsdb_dn->dn, "RMD_ADDTIME");
+       old_addtime = ldb_dn_get_extended_component(old_dsdb_dn->dn, "RMD_ADDTIME");
        if (old_addtime == NULL) {
                old_addtime = &tval;
        }
-       if (p != old_p) {
+       if (dsdb_dn != old_dsdb_dn) {
                ret = ldb_dn_set_extended_component(dn, "RMD_ADDTIME", old_addtime);
                if (ret != LDB_SUCCESS) return ret;
        }
@@ -1064,27 +1475,23 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct p
        if (ret != LDB_SUCCESS) return ret;
 
        /* update the USN */
-       ret = ldb_dn_set_extended_component(dn, "RMD_USN", &usnv);
+       ret = ldb_dn_set_extended_component(dn, "RMD_ORIGINATING_USN", &usnv);
+       if (ret != LDB_SUCCESS) return ret;
+
+       ret = ldb_dn_set_extended_component(dn, "RMD_LOCAL_USN", &local_usnv);
        if (ret != LDB_SUCCESS) return ret;
 
        /* increase the version by 1 */
-       old_version = ldb_dn_get_extended_component(old_p->dsdb_dn->dn, "RMD_VERSION");
-       if (old_version == NULL) {
-               vers = data_blob_string_const("0");
-       } else {
-               char *vstring;
-               vstring = talloc_strndup(dn, (const char *)old_version->data, old_version->length);
-               if (!vstring) {
-                       return LDB_ERR_OPERATIONS_ERROR;
-               }
-               vstring = talloc_asprintf(dn, "%lu",
-                                         (unsigned long)strtoul(vstring, NULL, 0)+1);
-               vers = data_blob_string_const(vstring);
+       status = dsdb_get_extended_dn_uint32(old_dsdb_dn->dn, &old_version, "RMD_VERSION");
+       if (NT_STATUS_IS_OK(status) && old_version >= version) {
+               version = old_version+1;
        }
+       vstring = talloc_asprintf(dn, "%lu", (unsigned long)version);
+       vers = data_blob_string_const(vstring);
        ret = ldb_dn_set_extended_component(dn, "RMD_VERSION", &vers);
        if (ret != LDB_SUCCESS) return ret;
 
-       dnstring = dsdb_dn_get_extended_linearized(mem_ctx, p->dsdb_dn, 1);
+       dnstring = dsdb_dn_get_extended_linearized(mem_ctx, dsdb_dn, 1);
        if (dnstring == NULL) {
                return LDB_ERR_OPERATIONS_ERROR;
        }
@@ -1097,12 +1504,14 @@ static int replmd_update_la_val(TALLOC_CTX *mem_ctx, struct ldb_val *v, struct p
   handle adding a linked attribute
  */
 static int replmd_modify_la_add(struct ldb_module *module,
+                               struct dsdb_schema *schema,
                                struct ldb_message *msg,
                                struct ldb_message_element *el,
                                struct ldb_message_element *old_el,
                                const struct dsdb_attribute *schema_attr,
                                uint64_t seq_num,
-                               time_t t)
+                               time_t t,
+                               struct GUID *msg_guid)
 {
        int i;
        struct parsed_dn *dns, *old_dns;
@@ -1113,6 +1522,9 @@ static int replmd_modify_la_add(struct ldb_module *module,
        unsigned old_num_values = old_el?old_el->num_values:0;
        const struct GUID *invocation_id;
        struct ldb_context *ldb = ldb_module_get_ctx(module);
+       NTTIME now;
+
+       unix_to_nt_time(&now, t);
 
        ret = get_parsed_dns(module, tmp_ctx, el, &dns, schema_attr->syntax->ldap_oid);
        if (ret != LDB_SUCCESS) {
@@ -1128,12 +1540,19 @@ static int replmd_modify_la_add(struct ldb_module *module,
 
        invocation_id = samdb_ntds_invocation_id(ldb);
        if (!invocation_id) {
+               talloc_free(tmp_ctx);
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
+       ret = replmd_check_upgrade_links(old_dns, old_num_values, invocation_id);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
        /* for each new value, see if it exists already with the same GUID */
        for (i=0; i<el->num_values; i++) {
-               struct parsed_dn *p = parsed_dn_find(old_dns, old_num_values, dns[i].guid);
+               struct parsed_dn *p = parsed_dn_find(old_dns, old_num_values, dns[i].guid, NULL);
                if (p == NULL) {
                        /* this is a new linked attribute value */
                        new_values = talloc_realloc(tmp_ctx, new_values, struct ldb_val, num_new_values+1);
@@ -1142,8 +1561,8 @@ static int replmd_modify_la_add(struct ldb_module *module,
                                talloc_free(tmp_ctx);
                                return LDB_ERR_OPERATIONS_ERROR;
                        }
-                       ret = replmd_build_la_val(new_values, &new_values[num_new_values], &dns[i],
-                                                 invocation_id, seq_num, t);
+                       ret = replmd_build_la_val(new_values, &new_values[num_new_values], dns[i].dsdb_dn,
+                                                 invocation_id, seq_num, seq_num, now, 0, false);
                        if (ret != LDB_SUCCESS) {
                                talloc_free(tmp_ctx);
                                return ret;
@@ -1152,20 +1571,27 @@ static int replmd_modify_la_add(struct ldb_module *module,
                } else {
                        /* this is only allowed if the GUID was
                           previously deleted. */
-                       const struct ldb_val *v;
-                       v = ldb_dn_get_extended_component(p->dsdb_dn->dn, "DELETED");
-                       if (v == NULL) {
+                       uint32_t rmd_flags = dsdb_dn_rmd_flags(p->dsdb_dn->dn);
+
+                       if (!(rmd_flags & DSDB_RMD_FLAG_DELETED)) {
                                ldb_asprintf_errstring(ldb, "Attribute %s already exists for target GUID %s",
                                                       el->name, GUID_string(tmp_ctx, p->guid));
                                talloc_free(tmp_ctx);
                                return LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS;
                        }
-                       ret = replmd_update_la_val(old_el->values, p->v, &dns[i], p, invocation_id, seq_num, t, false);
+                       ret = replmd_update_la_val(old_el->values, p->v, dns[i].dsdb_dn, p->dsdb_dn,
+                                                  invocation_id, seq_num, seq_num, now, 0, false);
                        if (ret != LDB_SUCCESS) {
                                talloc_free(tmp_ctx);
                                return ret;
                        }
                }
+
+               ret = replmd_add_backlink(module, schema, msg_guid, dns[i].guid, true, schema_attr, true);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
        }
 
        /* add the new ones on to the end of the old values, constructing a new el->values */
@@ -1197,12 +1623,14 @@ static int replmd_modify_la_add(struct ldb_module *module,
   handle deleting all active linked attributes
  */
 static int replmd_modify_la_delete(struct ldb_module *module,
+                                  struct dsdb_schema *schema,
                                   struct ldb_message *msg,
                                   struct ldb_message_element *el,
                                   struct ldb_message_element *old_el,
                                   const struct dsdb_attribute *schema_attr,
                                   uint64_t seq_num,
-                                  time_t t)
+                                  time_t t,
+                                  struct GUID *msg_guid)
 {
        int i;
        struct parsed_dn *dns, *old_dns;
@@ -1210,6 +1638,9 @@ static int replmd_modify_la_delete(struct ldb_module *module,
        int ret;
        const struct GUID *invocation_id;
        struct ldb_context *ldb = ldb_module_get_ctx(module);
+       NTTIME now;
+
+       unix_to_nt_time(&now, t);
 
        /* check if there is nothing to delete */
        if ((!old_el || old_el->num_values == 0) &&
@@ -1238,6 +1669,12 @@ static int replmd_modify_la_delete(struct ldb_module *module,
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
+       ret = replmd_check_upgrade_links(old_dns, old_el->num_values, invocation_id);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
        el->values = NULL;
 
        /* see if we are being asked to delete any links that
@@ -1245,16 +1682,16 @@ static int replmd_modify_la_delete(struct ldb_module *module,
        for (i=0; i<el->num_values; i++) {
                struct parsed_dn *p = &dns[i];
                struct parsed_dn *p2;
-               const struct ldb_val *v;
+               uint32_t rmd_flags;
 
-               p2 = parsed_dn_find(old_dns, old_el->num_values, p->guid);
+               p2 = parsed_dn_find(old_dns, old_el->num_values, p->guid, NULL);
                if (!p2) {
                        ldb_asprintf_errstring(ldb, "Attribute %s doesn't exist for target GUID %s",
                                               el->name, GUID_string(tmp_ctx, p->guid));
                        return LDB_ERR_NO_SUCH_ATTRIBUTE;
                }
-               v = ldb_dn_get_extended_component(p2->dsdb_dn->dn, "DELETED");
-               if (v) {
+               rmd_flags = dsdb_dn_rmd_flags(p2->dsdb_dn->dn);
+               if (rmd_flags & DSDB_RMD_FLAG_DELETED) {
                        ldb_asprintf_errstring(ldb, "Attribute %s already deleted for target GUID %s",
                                               el->name, GUID_string(tmp_ctx, p->guid));
                        return LDB_ERR_NO_SUCH_ATTRIBUTE;
@@ -1266,16 +1703,23 @@ static int replmd_modify_la_delete(struct ldb_module *module,
        */
        for (i=0; i<old_el->num_values; i++) {
                struct parsed_dn *p = &old_dns[i];
-               const struct ldb_val *v;
+               uint32_t rmd_flags;
 
-               if (dns && parsed_dn_find(dns, el->num_values, p->guid) == NULL) {
+               if (el->num_values && parsed_dn_find(dns, el->num_values, p->guid, NULL) == NULL) {
                        continue;
                }
 
-               v = ldb_dn_get_extended_component(p->dsdb_dn->dn, "DELETED");
-               if (v != NULL) continue;
+               rmd_flags = dsdb_dn_rmd_flags(p->dsdb_dn->dn);
+               if (rmd_flags & DSDB_RMD_FLAG_DELETED) continue;
+
+               ret = replmd_update_la_val(old_el->values, p->v, p->dsdb_dn, p->dsdb_dn,
+                                          invocation_id, seq_num, seq_num, now, 0, true);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
 
-               ret = replmd_update_la_val(old_el->values, p->v, p, p, invocation_id, seq_num, t, true);
+               ret = replmd_add_backlink(module, schema, msg_guid, old_dns[i].guid, false, schema_attr, true);
                if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
@@ -1298,12 +1742,14 @@ static int replmd_modify_la_delete(struct ldb_module *module,
   handle replacing a linked attribute
  */
 static int replmd_modify_la_replace(struct ldb_module *module,
+                                   struct dsdb_schema *schema,
                                    struct ldb_message *msg,
                                    struct ldb_message_element *el,
                                    struct ldb_message_element *old_el,
                                    const struct dsdb_attribute *schema_attr,
                                    uint64_t seq_num,
-                                   time_t t)
+                                   time_t t,
+                                   struct GUID *msg_guid)
 {
        int i;
        struct parsed_dn *dns, *old_dns;
@@ -1314,6 +1760,9 @@ static int replmd_modify_la_replace(struct ldb_module *module,
        struct ldb_val *new_values = NULL;
        uint32_t num_new_values = 0;
        unsigned old_num_values = old_el?old_el->num_values:0;
+       NTTIME now;
+
+       unix_to_nt_time(&now, t);
 
        /* check if there is nothing to replace */
        if ((!old_el || old_el->num_values == 0) &&
@@ -1338,22 +1787,34 @@ static int replmd_modify_la_replace(struct ldb_module *module,
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
+       ret = replmd_check_upgrade_links(old_dns, old_num_values, invocation_id);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
        /* mark all the old ones as deleted */
        for (i=0; i<old_num_values; i++) {
                struct parsed_dn *old_p = &old_dns[i];
                struct parsed_dn *p;
-               const struct ldb_val *v;
+               uint32_t rmd_flags = dsdb_dn_rmd_flags(old_p->dsdb_dn->dn);
+
+               if (rmd_flags & DSDB_RMD_FLAG_DELETED) continue;
 
-               p = parsed_dn_find(dns, el->num_values, old_p->guid);
+               ret = replmd_add_backlink(module, schema, msg_guid, old_dns[i].guid, false, schema_attr, false);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+
+               p = parsed_dn_find(dns, el->num_values, old_p->guid, NULL);
                if (p) {
                        /* we don't delete it if we are re-adding it */
                        continue;
                }
-               v = ldb_dn_get_extended_component(old_p->dsdb_dn->dn, "DELETED");
-               if (v) continue;
 
-               ret = replmd_update_la_val(old_el->values, old_p->v, old_p, old_p,
-                                          invocation_id, seq_num, t, true);
+               ret = replmd_update_la_val(old_el->values, old_p->v, old_p->dsdb_dn, old_p->dsdb_dn,
+                                          invocation_id, seq_num, seq_num, now, 0, true);
                if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
@@ -1368,11 +1829,11 @@ static int replmd_modify_la_replace(struct ldb_module *module,
 
                if (old_dns &&
                    (old_p = parsed_dn_find(old_dns,
-                                           old_num_values, p->guid)) != NULL) {
+                                           old_num_values, p->guid, NULL)) != NULL) {
                        /* update in place */
-                       ret = replmd_update_la_val(old_el->values, old_p->v, old_p,
-                                                  old_p, invocation_id,
-                                                  seq_num, t, false);
+                       ret = replmd_update_la_val(old_el->values, old_p->v, old_p->dsdb_dn,
+                                                  old_p->dsdb_dn, invocation_id,
+                                                  seq_num, seq_num, now, 0, false);
                        if (ret != LDB_SUCCESS) {
                                talloc_free(tmp_ctx);
                                return ret;
@@ -1386,14 +1847,20 @@ static int replmd_modify_la_replace(struct ldb_module *module,
                                talloc_free(tmp_ctx);
                                return LDB_ERR_OPERATIONS_ERROR;
                        }
-                       ret = replmd_build_la_val(new_values, &new_values[num_new_values], &dns[i],
-                                                 invocation_id, seq_num, t);
+                       ret = replmd_build_la_val(new_values, &new_values[num_new_values], dns[i].dsdb_dn,
+                                                 invocation_id, seq_num, seq_num, now, 0, false);
                        if (ret != LDB_SUCCESS) {
                                talloc_free(tmp_ctx);
                                return ret;
                        }
                        num_new_values++;
                }
+
+               ret = replmd_add_backlink(module, schema, msg_guid, dns[i].guid, true, schema_attr, false);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
        }
 
        /* add the new values to the end of old_el */
@@ -1436,6 +1903,7 @@ static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
        struct ldb_context *ldb = ldb_module_get_ctx(module);
        struct ldb_message *old_msg;
        struct dsdb_schema *schema = dsdb_get_schema(ldb);
+       struct GUID old_guid;
 
        if (seq_num == 0) {
                /* there the replmd_update_rpmd code has already
@@ -1462,6 +1930,8 @@ static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
        }
        old_msg = res->msgs[0];
 
+       old_guid = samdb_result_guid(old_msg, "objectGUID");
+
        for (i=0; i<msg->num_elements; i++) {
                struct ldb_message_element *el = &msg->elements[i];
                struct ldb_message_element *old_el, *new_el;
@@ -1484,13 +1954,13 @@ static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
                old_el = ldb_msg_find_element(old_msg, el->name);
                switch (el->flags & LDB_FLAG_MOD_MASK) {
                case LDB_FLAG_MOD_REPLACE:
-                       ret = replmd_modify_la_replace(module, msg, el, old_el, schema_attr, seq_num, t);
+                       ret = replmd_modify_la_replace(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                        break;
                case LDB_FLAG_MOD_DELETE:
-                       ret = replmd_modify_la_delete(module, msg, el, old_el, schema_attr, seq_num, t);
+                       ret = replmd_modify_la_delete(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                        break;
                case LDB_FLAG_MOD_ADD:
-                       ret = replmd_modify_la_add(module, msg, el, old_el, schema_attr, seq_num, t);
+                       ret = replmd_modify_la_add(module, schema, msg, el, old_el, schema_attr, seq_num, t, &old_guid);
                        break;
                default:
                        ldb_asprintf_errstring(ldb,
@@ -1506,7 +1976,7 @@ static int replmd_modify_handle_linked_attribs(struct ldb_module *module,
                }
                ldb_msg_add_empty(old_msg, el->name, 0, &new_el);
                new_el->num_values = el->num_values;
-               new_el->values = el->values;
+               new_el->values = talloc_steal(msg->elements, el->values);
 
                /* TODO: this relises a bit too heavily on the exact
                   behaviour of ldb_msg_find_element and
@@ -1532,6 +2002,7 @@ static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
        struct ldb_message *msg;
        time_t t = time(NULL);
        int ret;
+       bool is_urgent = false;
 
        /* do not manipulate our control entries */
        if (ldb_dn_is_special(req->op.mod.message->dn)) {
@@ -1555,7 +2026,10 @@ static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = replmd_update_rpmd(module, ac->schema, msg, &ac->seq_num, t);
+       ldb_msg_remove_attr(msg, "whenChanged");
+       ldb_msg_remove_attr(msg, "uSNChanged");
+
+       ret = replmd_update_rpmd(module, ac->schema, msg, &ac->seq_num, t, &is_urgent);
        if (ret != LDB_SUCCESS) {
                talloc_free(ac);
                return ret;
@@ -1571,6 +2045,8 @@ static int replmd_modify(struct ldb_module *module, struct ldb_request *req)
         * - replace the old object with the newly constructed one
         */
 
+       ac->is_urgent = is_urgent;
+
        ret = ldb_build_mod_req(&down_req, ldb, ac,
                                msg,
                                req->controls,
@@ -1714,6 +2190,329 @@ static int replmd_rename_callback(struct ldb_request *req, struct ldb_reply *are
        return ldb_next_request(ac->module, down_req);
 }
 
+/*
+   remove links from objects that point at this object when an object
+   is deleted
+ */
+static int replmd_delete_remove_link(struct ldb_module *module,
+                                    struct dsdb_schema *schema,
+                                    struct ldb_dn *dn,
+                                    struct ldb_message_element *el,
+                                    const struct dsdb_attribute *sa)
+{
+       int i;
+       TALLOC_CTX *tmp_ctx = talloc_new(module);
+       struct ldb_context *ldb = ldb_module_get_ctx(module);
+
+       for (i=0; i<el->num_values; i++) {
+               struct dsdb_dn *dsdb_dn;
+               NTSTATUS status;
+               int ret;
+               struct GUID guid2;
+               struct ldb_message *msg;
+               const struct dsdb_attribute *target_attr;
+               struct ldb_message_element *el2;
+               struct ldb_val dn_val;
+
+               if (dsdb_dn_is_deleted_val(&el->values[i])) {
+                       continue;
+               }
+
+               dsdb_dn = dsdb_dn_parse(tmp_ctx, ldb, &el->values[i], sa->syntax->ldap_oid);
+               if (!dsdb_dn) {
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+
+               status = dsdb_get_extended_dn_guid(dsdb_dn->dn, &guid2, "GUID");
+               if (!NT_STATUS_IS_OK(status)) {
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+
+               /* remove the link */
+               msg = ldb_msg_new(tmp_ctx);
+               if (!msg) {
+                       ldb_module_oom(module);
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+
+
+               msg->dn = dsdb_dn->dn;
+
+               target_attr = dsdb_attribute_by_linkID(schema, sa->linkID ^ 1);
+               if (target_attr == NULL) {
+                       continue;
+               }
+
+               ret = ldb_msg_add_empty(msg, target_attr->lDAPDisplayName, LDB_FLAG_MOD_DELETE, &el2);
+               if (ret != LDB_SUCCESS) {
+                       ldb_module_oom(module);
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+               dn_val = data_blob_string_const(ldb_dn_get_linearized(dn));
+               el2->values = &dn_val;
+               el2->num_values = 1;
+
+               ret = dsdb_module_modify(module, msg, DSDB_FLAG_OWN_MODULE);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+       }
+       talloc_free(tmp_ctx);
+       return LDB_SUCCESS;
+}
+
+
+/*
+  handle update of replication meta data for deletion of objects
+
+  This also handles the mapping of delete to a rename operation
+  to allow deletes to be replicated.
+ */
+static int replmd_delete(struct ldb_module *module, struct ldb_request *req)
+{
+       int ret = LDB_ERR_OTHER;
+       bool retb;
+       struct ldb_dn *old_dn, *new_dn;
+       const char *rdn_name;
+       const struct ldb_val *rdn_value, *new_rdn_value;
+       struct GUID guid;
+       struct ldb_context *ldb = ldb_module_get_ctx(module);
+       struct dsdb_schema *schema = dsdb_get_schema(ldb);
+       struct ldb_message *msg, *old_msg;
+       struct ldb_message_element *el;
+       TALLOC_CTX *tmp_ctx;
+       struct ldb_result *res, *parent_res;
+       const char *preserved_attrs[] = {
+               /* yes, this really is a hard coded list. See MS-ADTS
+                  section 3.1.1.5.5.1.1 */
+               "nTSecurityDescriptor", "attributeID", "attributeSyntax", "dNReferenceUpdate", "dNSHostName",
+               "flatName", "governsID", "groupType", "instanceType", "lDAPDisplayName", "legacyExchangeDN",
+               "isDeleted", "isRecycled", "lastKnownParent", "msDS-LastKnownRDN", "mS-DS-CreatorSID",
+               "mSMQOwnerID", "nCName", "objectClass", "distinguishedName", "objectGUID", "objectSid",
+               "oMSyntax", "proxiedObjectName", "name", "replPropertyMetaData", "sAMAccountName",
+               "securityIdentifier", "sIDHistory", "subClassOf", "systemFlags", "trustPartner", "trustDirection",
+               "trustType", "trustAttributes", "userAccountControl", "uSNChanged", "uSNCreated", "whenCreated",
+               "whenChanged", NULL};
+       uint32_t el_count = 0;
+       int i;
+
+       if (ldb_dn_is_special(req->op.del.dn)) {
+               return ldb_next_request(module, req);
+       }
+
+       tmp_ctx = talloc_new(ldb);
+
+       old_dn = ldb_dn_copy(tmp_ctx, req->op.del.dn);
+
+       /* we need the complete msg off disk, so we can work out which
+          attributes need to be removed */
+       ret = dsdb_module_search_dn(module, tmp_ctx, &res, old_dn, NULL,
+                                   DSDB_SEARCH_SHOW_DELETED |
+                                   DSDB_SEARCH_REVEAL_INTERNALS |
+                                   DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       old_msg = res->msgs[0];
+
+       if (ldb_msg_check_string_attribute(old_msg, "isDeleted", "TRUE")) {
+               struct auth_session_info *session_info =
+                       (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
+               if (security_session_user_level(session_info) != SECURITY_SYSTEM) {
+                       ldb_asprintf_errstring(ldb, "Refusing to delete deleted object %s",
+                                              ldb_dn_get_linearized(old_msg->dn));
+                       return LDB_ERR_UNWILLING_TO_PERFORM;
+               }
+
+               /* it is already deleted - really remove it this time */
+               talloc_free(tmp_ctx);
+               return ldb_next_request(module, req);
+       }
+
+       /* work out where we will be renaming this object to */
+       ret = dsdb_get_deleted_objects_dn(ldb, tmp_ctx, old_dn, &new_dn);
+       if (ret != LDB_SUCCESS) {
+               /* this is probably an attempted delete on a partition
+                * that doesn't allow delete operations, such as the
+                * schema partition */
+               ldb_asprintf_errstring(ldb, "No Deleted Objects container for DN %s",
+                                      ldb_dn_get_linearized(old_dn));
+               talloc_free(tmp_ctx);
+               return LDB_ERR_UNWILLING_TO_PERFORM;
+       }
+
+       rdn_name = ldb_dn_get_rdn_name(old_dn);
+       rdn_value = ldb_dn_get_rdn_val(old_dn);
+
+       /* get the objects GUID from the search we just did */
+       guid = samdb_result_guid(old_msg, "objectGUID");
+
+       /* Add a formatted child */
+       retb = ldb_dn_add_child_fmt(new_dn, "%s=%s\\0ADEL:%s",
+                                   rdn_name,
+                                   rdn_value->data,
+                                   GUID_string(tmp_ctx, &guid));
+       if (!retb) {
+               DEBUG(0,(__location__ ": Unable to add a formatted child to dn: %s",
+                               ldb_dn_get_linearized(new_dn)));
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       /*
+         now we need to modify the object in the following ways:
+
+         - add isDeleted=TRUE
+         - update rDN and name, with new rDN
+         - remove linked attributes
+         - remove objectCategory and sAMAccountType
+         - remove attribs not on the preserved list
+            - preserved if in above list, or is rDN
+         - remove all linked attribs from this object
+         - remove all links from other objects to this object
+         - add lastKnownParent
+         - update replPropertyMetaData?
+
+         see MS-ADTS "Tombstone Requirements" section 3.1.1.5.5.1.1
+        */
+
+       msg = ldb_msg_new(tmp_ctx);
+       if (msg == NULL) {
+               ldb_module_oom(module);
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       msg->dn = old_dn;
+
+       ret = ldb_msg_add_string(msg, "isDeleted", "TRUE");
+       if (ret != LDB_SUCCESS) {
+               DEBUG(0,(__location__ ": Failed to add isDeleted string to the msg\n"));
+               ldb_module_oom(module);
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
+
+       /* we also mark it as recycled, meaning this object can't be
+          recovered (we are stripping its attributes) */
+       if (dsdb_functional_level(ldb) >= DS_DOMAIN_FUNCTION_2008_R2) {
+               ret = ldb_msg_add_string(msg, "isRecycled", "TRUE");
+               if (ret != LDB_SUCCESS) {
+                       DEBUG(0,(__location__ ": Failed to add isRecycled string to the msg\n"));
+                       ldb_module_oom(module);
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+               msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
+       }
+
+       /* we need the storage form of the parent GUID */
+       ret = dsdb_module_search_dn(module, tmp_ctx, &parent_res,
+                                   ldb_dn_get_parent(tmp_ctx, old_dn), NULL,
+                                   DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
+                                   DSDB_SEARCH_REVEAL_INTERNALS);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       ret = ldb_msg_add_steal_string(msg, "lastKnownParent",
+                                      ldb_dn_get_extended_linearized(tmp_ctx, parent_res->msgs[0]->dn, 1));
+       if (ret != LDB_SUCCESS) {
+               DEBUG(0,(__location__ ": Failed to add lastKnownParent string to the msg\n"));
+               ldb_module_oom(module);
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       msg->elements[el_count++].flags = LDB_FLAG_MOD_ADD;
+
+       /* work out which of the old attributes we will be removing */
+       for (i=0; i<old_msg->num_elements; i++) {
+               const struct dsdb_attribute *sa;
+               el = &old_msg->elements[i];
+               sa = dsdb_attribute_by_lDAPDisplayName(schema, el->name);
+               if (!sa) {
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
+               if (ldb_attr_cmp(el->name, rdn_name) == 0) {
+                       /* don't remove the rDN */
+                       continue;
+               }
+
+               if (sa->linkID && sa->linkID & 1) {
+                       ret = replmd_delete_remove_link(module, schema, old_dn, el, sa);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return LDB_ERR_OPERATIONS_ERROR;
+                       }
+                       continue;
+               }
+
+               if (!sa->linkID && ldb_attr_in_list(preserved_attrs, el->name)) {
+                       continue;
+               }
+
+               ret = ldb_msg_add_empty(msg, el->name, LDB_FLAG_MOD_DELETE, &el);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       ldb_module_oom(module);
+                       return ret;
+               }
+       }
+
+       /* work out what the new rdn value is, for updating the
+          rDN and name fields */
+       new_rdn_value = ldb_dn_get_rdn_val(new_dn);
+       ret = ldb_msg_add_value(msg, rdn_name, new_rdn_value, &el);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+       el->flags = LDB_FLAG_MOD_REPLACE;
+
+       el = ldb_msg_find_element(old_msg, "name");
+       if (el) {
+               ret = ldb_msg_add_value(msg, "name", new_rdn_value, &el);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
+               el->flags = LDB_FLAG_MOD_REPLACE;
+       }
+
+       ret = dsdb_module_modify(module, msg, DSDB_FLAG_OWN_MODULE);
+       if (ret != LDB_SUCCESS) {
+               ldb_asprintf_errstring(ldb, "replmd_delete: Failed to modify object %s in delete - %s",
+                                      ldb_dn_get_linearized(old_dn), ldb_errstring(ldb));
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       /* now rename onto the new DN */
+       ret = dsdb_module_rename(module, old_dn, new_dn, 0);
+       if (ret != LDB_SUCCESS){
+               DEBUG(0,(__location__ ": Failed to rename object from '%s' to '%s' - %s\n",
+                        ldb_dn_get_linearized(old_dn),
+                        ldb_dn_get_linearized(new_dn),
+                        ldb_errstring(ldb)));
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       talloc_free(tmp_ctx);
+
+       return ldb_module_done(req, NULL, NULL, LDB_SUCCESS);
+}
+
+
 
 static int replmd_replicated_request_error(struct replmd_replicated_request *ar, int ret)
 {
@@ -1778,14 +2577,15 @@ static int replmd_replicated_apply_add(struct replmd_replicated_request *ar)
 
        /* remove any message elements that have zero values */
        for (i=0; i<msg->num_elements; i++) {
-               if (msg->elements[i].num_values == 0) {
+               struct ldb_message_element *el = &msg->elements[i];
+
+               if (el->num_values == 0) {
                        DEBUG(4,(__location__ ": Removing attribute %s with num_values==0\n",
-                                msg->elements[i].name));
-                       memmove(&msg->elements[i], 
-                               &msg->elements[i+1], 
-                               sizeof(msg->elements[i])*(msg->num_elements - (i+1)));
+                                el->name));
+                       memmove(el, el+1, sizeof(*el)*(msg->num_elements - (i+1)));
                        msg->num_elements--;
                        i--;
+                       continue;
                }
        }
        
@@ -1829,25 +2629,38 @@ static int replmd_replicated_apply_add(struct replmd_replicated_request *ar)
        return ldb_next_request(ar->module, change_req);
 }
 
-static int replmd_replPropertyMetaData1_conflict_compare(struct replPropertyMetaData1 *m1,
-                                                        struct replPropertyMetaData1 *m2)
+/*
+   return true if an update is newer than an existing entry
+   see section 5.11 of MS-ADTS
+*/
+static bool replmd_update_is_newer(const struct GUID *current_invocation_id,
+                                  const struct GUID *update_invocation_id,
+                                  uint32_t current_version,
+                                  uint32_t update_version,
+                                  NTTIME current_change_time,
+                                  NTTIME update_change_time)
 {
-       int ret;
-
-       if (m1->version != m2->version) {
-               return m1->version - m2->version;
+       if (update_version != current_version) {
+               return update_version > current_version;
        }
-
-       if (m1->originating_change_time != m2->originating_change_time) {
-               return m1->originating_change_time - m2->originating_change_time;
+       if (update_change_time > current_change_time) {
+               return true;
        }
-
-       ret = GUID_compare(&m1->originating_invocation_id, &m2->originating_invocation_id);
-       if (ret != 0) {
-               return ret;
+       if (update_change_time == current_change_time) {
+               return GUID_compare(update_invocation_id, current_invocation_id) > 0;
        }
+       return false;
+}
 
-       return m1->originating_usn - m2->originating_usn;
+static bool replmd_replPropertyMetaData1_is_newer(struct replPropertyMetaData1 *cur_m,
+                                                 struct replPropertyMetaData1 *new_m)
+{
+       return replmd_update_is_newer(&cur_m->originating_invocation_id,
+                                     &new_m->originating_invocation_id,
+                                     cur_m->version,
+                                     new_m->version,
+                                     cur_m->originating_change_time,
+                                     new_m->originating_change_time);
 }
 
 static int replmd_replicated_apply_merge(struct replmd_replicated_request *ar)
@@ -1878,7 +2691,9 @@ static int replmd_replicated_apply_merge(struct replmd_replicated_request *ar)
                ldb_debug(ldb, LDB_DEBUG_TRACE, "replmd_replicated_request rename %s => %s\n",
                          ldb_dn_get_linearized(ar->search_msg->dn),
                          ldb_dn_get_linearized(msg->dn));
-               if (ldb_rename(ldb, ar->search_msg->dn, msg->dn) != LDB_SUCCESS) {
+               if (dsdb_module_rename(ar->module,
+                                      ar->search_msg->dn, msg->dn,
+                                      DSDB_FLAG_OWN_MODULE) != LDB_SUCCESS) {
                        ldb_debug(ldb, LDB_DEBUG_FATAL, "replmd_replicated_request rename %s => %s failed - %s\n",
                                  ldb_dn_get_linearized(ar->search_msg->dn),
                                  ldb_dn_get_linearized(msg->dn),
@@ -1922,21 +2737,28 @@ static int replmd_replicated_apply_merge(struct replmd_replicated_request *ar)
                bool found = false;
 
                for (j=0; j < ni; j++) {
-                       int cmp;
+                       bool cmp;
 
                        if (rmd->ctr.ctr1.array[i].attid != nmd.ctr.ctr1.array[j].attid) {
                                continue;
                        }
 
-                       cmp = replmd_replPropertyMetaData1_conflict_compare(&rmd->ctr.ctr1.array[i],
-                                                                           &nmd.ctr.ctr1.array[j]);
-                       if (cmp > 0) {
+                       cmp = replmd_replPropertyMetaData1_is_newer(&nmd.ctr.ctr1.array[j],
+                                                                   &rmd->ctr.ctr1.array[i]);
+                       if (cmp) {
                                /* replace the entry */
                                nmd.ctr.ctr1.array[j] = rmd->ctr.ctr1.array[i];
                                found = true;
                                break;
                        }
 
+                       if (rmd->ctr.ctr1.array[i].attid != DRSUAPI_ATTRIBUTE_instanceType) {
+                               DEBUG(1,("Discarding older DRS attribute update to %s on %s from %s\n",
+                                        msg->elements[i-removed_attrs].name,
+                                        ldb_dn_get_linearized(msg->dn),
+                                        GUID_string(ar, &rmd->ctr.ctr1.array[i].originating_invocation_id)));
+                       }
+
                        /* we don't want to apply this change so remove the attribute */
                        ldb_msg_remove_element(msg, &msg->elements[i-removed_attrs]);
                        removed_attrs++;
@@ -2638,25 +3460,22 @@ static int replmd_process_linked_attribute(struct ldb_module *module,
        struct drsuapi_DsReplicaLinkedAttribute *la = la_entry->la;
        struct ldb_context *ldb = ldb_module_get_ctx(module);
        struct dsdb_schema *schema = dsdb_get_schema(ldb);
-       struct drsuapi_DsReplicaObjectIdentifier3 target;
        struct ldb_message *msg;
        TALLOC_CTX *tmp_ctx = talloc_new(la_entry);
-       struct ldb_request *mod_req;
        int ret;
        const struct dsdb_attribute *attr;
-       struct ldb_dn *target_dn;
        struct dsdb_dn *dsdb_dn;
        uint64_t seq_num = 0;
-       struct drsuapi_DsReplicaAttribute drs;
-       struct drsuapi_DsAttributeValue val;
-       struct ldb_message_element el;
-       const struct ldb_val *guid;
+       struct ldb_message_element *old_el;
        WERROR status;
        time_t t = time(NULL);
-
-       drs.value_ctr.num_values = 1;
-       drs.value_ctr.values = &val;
-       val.blob = la->value.blob;
+       struct ldb_result *res;
+       const char *attrs[2];
+       struct parsed_dn *pdn_list, *pdn;
+       struct GUID guid = GUID_zero();
+       NTSTATUS ntstatus;
+       bool active = (la->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)?true:false;
+       const struct GUID *our_invocation_id;
 
 /*
 linked_attributes[0]:                                                     
@@ -2701,153 +3520,212 @@ linked_attributes[0]:
                return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       status = attr->syntax->drsuapi_to_ldb(ldb, schema, attr, &drs, tmp_ctx, &el);
-
-       /* construct a modify request for this attribute change */
-       msg = ldb_msg_new(tmp_ctx);
-       if (!msg) {
-               ldb_oom(ldb);
-               talloc_free(tmp_ctx);
-               return LDB_ERR_OPERATIONS_ERROR;
-       }
+       attrs[0] = attr->lDAPDisplayName;
+       attrs[1] = NULL;
 
-       ret = dsdb_find_dn_by_guid(ldb, tmp_ctx, 
-                                  GUID_string(tmp_ctx, &la->identifier->guid), &msg->dn);
+       /* get the existing message from the db for the object with
+          this GUID, returning attribute being modified. We will then
+          use this msg as the basis for a modify call */
+       ret = dsdb_module_search(module, tmp_ctx, &res, NULL, LDB_SCOPE_SUBTREE, attrs,
+                                DSDB_SEARCH_SEARCH_ALL_PARTITIONS |
+                                DSDB_SEARCH_SHOW_DELETED |
+                                DSDB_SEARCH_SHOW_DN_IN_STORAGE_FORMAT |
+                                DSDB_SEARCH_REVEAL_INTERNALS,
+                                "objectGUID=%s", GUID_string(tmp_ctx, &la->identifier->guid));
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
        }
+       if (res->count != 1) {
+               ldb_asprintf_errstring(ldb, "DRS linked attribute for GUID %s - DN not found",
+                                      GUID_string(tmp_ctx, &la->identifier->guid));
+               talloc_free(tmp_ctx);
+               return LDB_ERR_NO_SUCH_OBJECT;
+       }
+       msg = res->msgs[0];
 
-       el.name = attr->lDAPDisplayName;
-       if (la->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE) {
-               ret = ldb_msg_add(msg, &el, LDB_FLAG_MOD_ADD);
+       if (msg->num_elements == 0) {
+               ret = ldb_msg_add_empty(msg, attr->lDAPDisplayName, LDB_FLAG_MOD_REPLACE, &old_el);
+               if (ret != LDB_SUCCESS) {
+                       ldb_module_oom(module);
+                       talloc_free(tmp_ctx);
+                       return LDB_ERR_OPERATIONS_ERROR;
+               }
        } else {
-               ret = ldb_msg_add(msg, &el, LDB_FLAG_MOD_DELETE);
+               old_el = &msg->elements[0];
+               old_el->flags = LDB_FLAG_MOD_REPLACE;
        }
+
+       /* parse the existing links */
+       ret = get_parsed_dns(module, tmp_ctx, old_el, &pdn_list, attr->syntax->ldap_oid);
        if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
                return ret;
        }
 
-       dsdb_dn = dsdb_dn_parse(tmp_ctx, ldb, &el.values[0], attr->syntax->ldap_oid);
-       if (!dsdb_dn) {
-               DEBUG(0,(__location__ ": Failed to parse just-generated DN\n"));
+       /* get our invocationId */
+       our_invocation_id = samdb_ntds_invocation_id(ldb);
+       if (!our_invocation_id) {
+               ldb_debug_set(ldb, LDB_DEBUG_ERROR, __location__ ": unable to find invocationId\n");
                talloc_free(tmp_ctx);
-               return LDB_ERR_INVALID_DN_SYNTAX;
+               return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       guid = ldb_dn_get_extended_component(dsdb_dn->dn, "GUID");
-       if (!guid) {
-               DEBUG(0,(__location__ ": Failed to parse GUID from just-generated DN\n"));
+       ret = replmd_check_upgrade_links(pdn_list, old_el->num_values, our_invocation_id);
+       if (ret != LDB_SUCCESS) {
                talloc_free(tmp_ctx);
-               return LDB_ERR_INVALID_DN_SYNTAX;
+               return ret;
        }
 
-       ret = dsdb_find_dn_by_guid(ldb, tmp_ctx, ldb_binary_encode(tmp_ctx, *guid), &target_dn);
-       if (ret != LDB_SUCCESS) {
-               /* If this proves to be a problem in the future, then
-                * just remove the return - perhaps we can just use
-                * the details the replication peer supplied */
-
-               DEBUG(0,(__location__ ": Failed to map GUID %s to DN\n", GUID_string(tmp_ctx, &target.guid)));
-               talloc_free(tmp_ctx);
+       status = dsdb_dn_la_from_blob(ldb, attr, schema, tmp_ctx, la->value.blob, &dsdb_dn);
+       if (!W_ERROR_IS_OK(status)) {
+               ldb_asprintf_errstring(ldb, "Failed to parsed linked attribute blob for %s on %s - %s\n",
+                                      old_el->name, ldb_dn_get_linearized(msg->dn), win_errstr(status));
                return LDB_ERR_OPERATIONS_ERROR;
-       } else {
+       }
 
-               /* Now update with full DN we just found in the DB (including extended components) */
-               dsdb_dn->dn = target_dn;
-               /* Now make a linearized version, using the original binary components (if any) */
-               el.values[0] = data_blob_string_const(dsdb_dn_get_extended_linearized(tmp_ctx, dsdb_dn, 1));
+       ntstatus = dsdb_get_extended_dn_guid(dsdb_dn->dn, &guid, "GUID");
+       if (!NT_STATUS_IS_OK(ntstatus) && active) {
+               ldb_asprintf_errstring(ldb, "Failed to find GUID in linked attribute blob for %s on %s from %s",
+                                      old_el->name,
+                                      ldb_dn_get_linearized(dsdb_dn->dn),
+                                      ldb_dn_get_linearized(msg->dn));
+               return LDB_ERR_OPERATIONS_ERROR;
        }
 
-       ret = replmd_update_rpmd(module, schema, msg, &seq_num, t);
+       /* re-resolve the DN by GUID, as the DRS server may give us an
+          old DN value */
+       ret = dsdb_module_dn_by_guid(module, dsdb_dn, &guid, &dsdb_dn->dn);
        if (ret != LDB_SUCCESS) {
+               ldb_asprintf_errstring(ldb, __location__ ": Failed to re-resolve GUID %s",
+                                      GUID_string(tmp_ctx, &guid));
                talloc_free(tmp_ctx);
                return ret;
        }
 
-       /* we only change whenChanged and uSNChanged if the seq_num
-          has changed */
-       if (seq_num != 0) {
-               if (add_time_element(msg, "whenChanged", t) != LDB_SUCCESS) {
+       /* see if this link already exists */
+       pdn = parsed_dn_find(pdn_list, old_el->num_values, &guid, dsdb_dn->dn);
+       if (pdn != NULL) {
+               /* see if this update is newer than what we have already */
+               struct GUID invocation_id = GUID_zero();
+               uint32_t version = 0;
+               NTTIME change_time = 0;
+               uint32_t rmd_flags = dsdb_dn_rmd_flags(pdn->dsdb_dn->dn);
+
+               dsdb_get_extended_dn_guid(pdn->dsdb_dn->dn, &invocation_id, "RMD_INVOCID");
+               dsdb_get_extended_dn_uint32(pdn->dsdb_dn->dn, &version, "RMD_VERSION");
+               dsdb_get_extended_dn_nttime(pdn->dsdb_dn->dn, &change_time, "RMD_CHANGETIME");
+
+               if (!replmd_update_is_newer(&invocation_id,
+                                           &la->meta_data.originating_invocation_id,
+                                           version,
+                                           la->meta_data.version,
+                                           change_time,
+                                           la->meta_data.originating_change_time)) {
+                       DEBUG(1,("Discarding older DRS linked attribute update to %s on %s from %s\n",
+                                old_el->name, ldb_dn_get_linearized(msg->dn),
+                                GUID_string(tmp_ctx, &la->meta_data.originating_invocation_id)));
                        talloc_free(tmp_ctx);
-                       return LDB_ERR_OPERATIONS_ERROR;
+                       return LDB_SUCCESS;
                }
 
-               if (add_uint64_element(msg, "uSNChanged", seq_num) != LDB_SUCCESS) {
+               /* get a seq_num for this change */
+               ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
+               if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
-                       return LDB_ERR_OPERATIONS_ERROR;
+                       return ret;
                }
-       }
 
-       ret = ldb_build_mod_req(&mod_req, ldb, tmp_ctx,
-                               msg,
-                               NULL,
-                               NULL, 
-                               ldb_op_default_callback,
-                               NULL);
-       if (ret != LDB_SUCCESS) {
-               talloc_free(tmp_ctx);
-               return ret;
-       }
-       talloc_steal(mod_req, msg);
-
-       if (DEBUGLVL(4)) {
-               DEBUG(4,("Applying DRS linked attribute change:\n%s\n",
-                        ldb_ldif_message_string(ldb, tmp_ctx, LDB_CHANGETYPE_MODIFY, msg)));
-       }
-
-       /* Run the new request */
-       ret = ldb_next_request(module, mod_req);
+               if (!(rmd_flags & DSDB_RMD_FLAG_DELETED)) {
+                       /* remove the existing backlink */
+                       ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid, false, attr, false);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return ret;
+                       }
+               }
 
-       /* we need to wait for this to finish, as we are being called
-          from the synchronous end_transaction hook of this module */
-       if (ret == LDB_SUCCESS) {
-               ret = ldb_wait(mod_req->handle, LDB_WAIT_ALL);
-       }
+               ret = replmd_update_la_val(tmp_ctx, pdn->v, dsdb_dn, pdn->dsdb_dn,
+                                          &la->meta_data.originating_invocation_id,
+                                          la->meta_data.originating_usn, seq_num,
+                                          la->meta_data.originating_change_time,
+                                          la->meta_data.version,
+                                          !active);
+               if (ret != LDB_SUCCESS) {
+                       talloc_free(tmp_ctx);
+                       return ret;
+               }
 
-       if (ret == LDB_ERR_ATTRIBUTE_OR_VALUE_EXISTS) {
-               /* the link destination exists, we need to update it
-                * by deleting the old one for the same DN then adding
-                * the new one */
-               msg->elements = talloc_realloc(msg, msg->elements,
-                                              struct ldb_message_element,
-                                              msg->num_elements+1);
-               if (msg->elements == NULL) {
-                       ldb_oom(ldb);
+               if (active) {
+                       /* add the new backlink */
+                       ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid, true, attr, false);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return ret;
+                       }
+               }
+       } else {
+               /* get a seq_num for this change */
+               ret = ldb_sequence_number(ldb, LDB_SEQ_NEXT, &seq_num);
+               if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
+                       return ret;
+               }
+
+               old_el->values = talloc_realloc(msg->elements, old_el->values,
+                                               struct ldb_val, old_el->num_values+1);
+               if (!old_el->values) {
+                       ldb_module_oom(module);
                        return LDB_ERR_OPERATIONS_ERROR;
                }
-               /* this relies on the backend matching the old entry
-                  only by the DN portion of the extended DN */
-               msg->elements[1] = msg->elements[0];
-               msg->elements[0].flags = LDB_FLAG_MOD_DELETE;
-               msg->num_elements++;
-
-               ret = ldb_build_mod_req(&mod_req, ldb, tmp_ctx,
-                                       msg,
-                                       NULL,
-                                       NULL, 
-                                       ldb_op_default_callback,
-                                       NULL);
+               old_el->num_values++;
+
+               ret = replmd_build_la_val(tmp_ctx, &old_el->values[old_el->num_values-1], dsdb_dn,
+                                         &la->meta_data.originating_invocation_id,
+                                         la->meta_data.originating_usn, seq_num,
+                                         la->meta_data.originating_change_time,
+                                         la->meta_data.version,
+                                         (la->flags & DRSUAPI_DS_LINKED_ATTRIBUTE_FLAG_ACTIVE)?false:true);
                if (ret != LDB_SUCCESS) {
                        talloc_free(tmp_ctx);
                        return ret;
                }
 
-               /* Run the new request */
-               ret = ldb_next_request(module, mod_req);
-               
-               if (ret == LDB_SUCCESS) {
-                       ret = ldb_wait(mod_req->handle, LDB_WAIT_ALL);
+               if (active) {
+                       ret = replmd_add_backlink(module, schema, &la->identifier->guid, &guid,
+                                                 true, attr, false);
+                       if (ret != LDB_SUCCESS) {
+                               talloc_free(tmp_ctx);
+                               return ret;
+                       }
                }
        }
 
+       /* we only change whenChanged and uSNChanged if the seq_num
+          has changed */
+       if (add_time_element(msg, "whenChanged", t) != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       if (add_uint64_element(msg, "uSNChanged", seq_num) != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return LDB_ERR_OPERATIONS_ERROR;
+       }
+
+       ret = dsdb_check_single_valued_link(attr, old_el);
+       if (ret != LDB_SUCCESS) {
+               talloc_free(tmp_ctx);
+               return ret;
+       }
+
+       ret = dsdb_module_modify(module, msg, DSDB_MODIFY_RELAX);
        if (ret != LDB_SUCCESS) {
-               ldb_debug(ldb, LDB_DEBUG_WARNING, "Failed to apply linked attribute change '%s' %s\n",
+               ldb_debug(ldb, LDB_DEBUG_WARNING, "Failed to apply linked attribute change '%s'\n%s\n",
                          ldb_errstring(ldb),
                          ldb_ldif_message_string(ldb, tmp_ctx, LDB_CHANGETYPE_MODIFY, msg));
-               ret = LDB_SUCCESS;
+               talloc_free(tmp_ctx);
+               return ret;
        }
        
        talloc_free(tmp_ctx);
@@ -2877,9 +3755,7 @@ static int replmd_start_transaction(struct ldb_module *module)
        /* create our private structure for this transaction */
        struct replmd_private *replmd_private = talloc_get_type(ldb_module_get_private(module),
                                                                struct replmd_private);
-       talloc_free(replmd_private->la_ctx);
-       replmd_private->la_list = NULL;
-       replmd_private->la_ctx = NULL;
+       replmd_txn_cleanup(replmd_private);
 
        /* free any leftover mod_usn records from cancelled
           transactions */
@@ -2901,28 +3777,33 @@ static int replmd_prepare_commit(struct ldb_module *module)
        struct replmd_private *replmd_private = 
                talloc_get_type(ldb_module_get_private(module), struct replmd_private);
        struct la_entry *la, *prev;
+       struct la_backlink *bl;
        int ret;
 
        /* walk the list backwards, to do the first entry first, as we
         * added the entries with DLIST_ADD() which puts them at the
         * start of the list */
-       for (la = replmd_private->la_list; la && la->next; la=la->next) ;
-
-       for (; la; la=prev) {
-               prev = la->prev;
+       for (la = DLIST_TAIL(replmd_private->la_list); la; la=prev) {
+               prev = DLIST_PREV(la);
                DLIST_REMOVE(replmd_private->la_list, la);
                ret = replmd_process_linked_attribute(module, la);
                if (ret != LDB_SUCCESS) {
-                       talloc_free(replmd_private->la_ctx);
-                       replmd_private->la_list = NULL;
-                       replmd_private->la_ctx = NULL;
+                       replmd_txn_cleanup(replmd_private);
                        return ret;
                }
        }
 
-       talloc_free(replmd_private->la_ctx);
-       replmd_private->la_list = NULL;
-       replmd_private->la_ctx = NULL;
+       /* process our backlink list, creating and deleting backlinks
+          as necessary */
+       for (bl=replmd_private->la_backlinks; bl; bl=bl->next) {
+               ret = replmd_process_backlink(module, bl);
+               if (ret != LDB_SUCCESS) {
+                       replmd_txn_cleanup(replmd_private);
+                       return ret;
+               }
+       }
+
+       replmd_txn_cleanup(replmd_private);
 
        /* possibly change @REPLCHANGED */
        ret = replmd_notify_store(module);
@@ -2937,9 +3818,8 @@ static int replmd_del_transaction(struct ldb_module *module)
 {
        struct replmd_private *replmd_private = 
                talloc_get_type(ldb_module_get_private(module), struct replmd_private);
-       talloc_free(replmd_private->la_ctx);
-       replmd_private->la_list = NULL;
-       replmd_private->la_ctx = NULL;
+       replmd_txn_cleanup(replmd_private);
+
        return ldb_next_del_trans(module);
 }
 
@@ -2950,6 +3830,7 @@ _PUBLIC_ const struct ldb_module_ops ldb_repl_meta_data_module_ops = {
        .add               = replmd_add,
        .modify            = replmd_modify,
        .rename            = replmd_rename,
+       .del               = replmd_delete,
        .extended          = replmd_extended,
        .start_transaction = replmd_start_transaction,
        .prepare_commit    = replmd_prepare_commit,