CREATE OR REPLACE FUNCTION plpgsql_call_handler()
  RETURNS language_handler AS
'/usr/local/pgsql/lib/plpgsql.so', 'plpgsql_call_handler'
  LANGUAGE 'c' VOLATILE;
CREATE OR REPLACE FUNCTION plpgsql_validator(oid)
  RETURNS void AS
'/usr/local/pgsql/lib/plpgsql.so', 'plpgsql_validator'
  LANGUAGE 'c' VOLATILE;
 CREATE TRUSTED PROCEDURAL LANGUAGE 'plpgsql'
  HANDLER plpgsql_call_handler;

CREATE TYPE in_out_traf AS
   (ip_addr inet,
    in_traf int4,
    out_traf int4);

CREATE OR REPLACE FUNCTION test() RETURNS SETOF in_out_traf AS
$$
declare 
    r in_out_traf;
begin
    r.ip_addr = '192.168.1.1';
    r.in_traf =  123 ;
    r.out_traf =  789 ;
 return next r;
end
$$
LANGUAGE plpgsql;

select test();