Prevent multiple nodes being registered with the same name.

Fixes GitHub #192.

dbutils.c

@@ -31,6 +31,7 @@
 char repmgr_schema[MAXLEN] = "";
 char repmgr_schema_quoted[MAXLEN] = "";
 
+static int _get_node_record(PGconn *conn, char *cluster, char *sqlquery, t_node_info *node_info);
 
 PGconn *
 _establish_db_connection(const char *conninfo, const bool exit_on_error, const bool log_notice)
@@ -1681,8 +1682,7 @@ int
 get_node_record(PGconn *conn, char *cluster, int node_id, t_node_info *node_info)
 {
 	char		sqlquery[QUERY_STR_LEN];
-	PGresult   *res;
-	int         ntuples;
+	int		    result;
 
 	sqlquery_snprintf(
 		sqlquery,
@@ -1696,6 +1696,49 @@ get_node_record(PGconn *conn, char *cluster, int node_id, t_node_info *node_info
 
 	log_verbose(LOG_DEBUG, "get_node_record():\n%s\n", sqlquery);
 
+	result = _get_node_record(conn, cluster, sqlquery, node_info);
+
+	if (result == 0)
+	{
+		log_verbose(LOG_DEBUG, "get_node_record(): no record found for node %i\n", node_id);
+	}
+
+	return result;
+}
+
+int
+get_node_record_by_name(PGconn *conn, char *cluster, const char *node_name, t_node_info *node_info)
+{
+	char		sqlquery[QUERY_STR_LEN];
+	int result;
+
+	sqlquery_snprintf(
+		sqlquery,
+		"SELECT id, type, upstream_node_id, name, conninfo, slot_name, priority, active"
+		"  FROM %s.repl_nodes "
+		" WHERE cluster = '%s' "
+		"   AND node_name = %s",
+		get_repmgr_schema_quoted(conn),
+		cluster,
+		node_name);
+
+	result = _get_node_record(conn, cluster, sqlquery, node_info);
+
+	if (result == 0)
+	{
+		log_verbose(LOG_DEBUG, "get_node_record(): no record found for node %s\n", node_name);
+	}
+
+	return result;
+}
+
+
+static int
+_get_node_record(PGconn *conn, char *cluster, char *sqlquery, t_node_info *node_info)
+{
+	int         ntuples;
+	PGresult   *res;
+
 	res = PQexec(conn, sqlquery);
 	if (PQresultStatus(res) != PGRES_TUPLES_OK)
 	{
@@ -1706,7 +1749,6 @@ get_node_record(PGconn *conn, char *cluster, int node_id, t_node_info *node_info
 
 	if (ntuples == 0)
 	{
-		log_verbose(LOG_DEBUG, "get_node_record(): no record found for node %i\n", node_id);
 		return 0;
 	}
 
@@ -1727,6 +1769,9 @@ get_node_record(PGconn *conn, char *cluster, int node_id, t_node_info *node_info
 }
 
 
+
+
+
 int
 get_node_replication_state(PGconn *conn, char *node_name, char *output)
 {

dbutils.h

@@ -125,6 +125,7 @@ bool		witness_copy_node_records(PGconn *masterconn, PGconn *witnessconn, char *c
 bool		create_node_record(PGconn *conn, char *action, int node, char *type, int upstream_node, char *cluster_name, char *node_name, char *conninfo, int priority, char *slot_name, bool active);
 bool		delete_node_record(PGconn *conn, int node, char *action);
 int			get_node_record(PGconn *conn, char *cluster, int node_id, t_node_info *node_info);
+int			get_node_record_by_name(PGconn *conn, char *cluster, const char *node_name, t_node_info *node_info);
 bool        update_node_record_status(PGconn *conn, char *cluster_name, int this_node_id, char *type, int upstream_node_id, bool active);
 bool        update_node_record_set_upstream(PGconn *conn, char *cluster_name, int this_node_id, int new_upstream_node_id);
 bool        create_event_record(PGconn *conn, t_configuration_options *options, int node_id, char *event, bool successful, char *details);

repmgr.c

@@ -1127,8 +1127,9 @@ do_standby_register(void)
 	PGconn	   *master_conn;
 	int			ret;
 
-
 	bool		record_created;
+	t_node_info node_record;
+	int			node_result;
 
 	log_info(_("connecting to standby database\n"));
 	conn = establish_db_connection(options.conninfo, true);
@@ -1185,6 +1186,28 @@ do_standby_register(void)
 		}
 	}
 
+	/*
+	 * Check that an active node with the same node_name doesn't exist already
+	 */
+
+	node_result = get_node_record_by_name(master_conn,
+										  options.cluster_name,
+										  options.node_name,
+										  &node_record);
+
+	if (node_result)
+	{
+		if (node_record.active == true)
+		{
+			log_err(_("Node %i exists already with node_name \"%s\""),
+					  node_record.node_id,
+					  options.node_name);
+			PQfinish(master_conn);
+			PQfinish(conn);
+			exit(ERR_BAD_CONFIG);
+		}
+	}
+
 	record_created = create_node_record(master_conn,
 										"standby register",
 										options.node,