1The IDNA codec decoder used on DNS hostnames by :mod:`socket` or :mod:`asyncio` 2related name resolution functions no longer involves a quadratic algorithm. 3This prevents a potential CPU denial of service if an out-of-spec excessive 4length hostname involving bidirectional characters were decoded. Some protocols 5such as :mod:`urllib` http ``3xx`` redirects potentially allow for an attacker 6to supply such a name. 7