Validate and parse DNS record data for SRV record(s)
    :param rdata: DNS record data
    :return: dict w/fields

def srv_rec(rdatas):
    '''
    Validate and parse DNS record data for SRV record(s)
    :param rdata: DNS record data
    :return: dict w/fields
    '''
    rschema = OrderedDict((
        ('prio', int),
        ('weight', int),
        ('port', _to_port),
        ('name', str),
    ))
    return _data2rec_group(rschema, rdatas, 'prio')