until( eof DATA ) {
    read DATA, my $header, BLOCKHDR or die;
    ## Do stuff with $header;
    
    for my $cdr ( 1 .. MAXRECORD ) {
        read DATA, my $record, CDRLEN or die;
        ## Do stuff with $record
    }
    
    read DATA, my $trailer, BLOCKTRL or die;
    ## Do stuff with $trailer
}