Add support for wildcard DNS records

[ivank]

I couldn't get wildcard DNS records working with twisted.names. I followed names/howto/names.html and my A('*.example-domain.com', '127.0.0.1') did not work as expected.

There's a patch from 2004 that didn't make it into trunk (afaik):

​http://twistedmatrix.com/pipermail/twisted-python/2004-October/008851.html

names/howto/names.html should also be updated with an example of wildcard records.

RFC reference:

• Updated info about "The Role of Wildcards in the Domain Name System": ​https://tools.ietf.org/html/rfc4592
• Serving wildcard records: ​https://tools.ietf.org/html/rfc1034#section-4.3.3
• Caching wildcard records: ​https://tools.ietf.org/html/rfc1035#section-7.4

[Jean-Paul Calderone]

I'd prefer a better interface. "*.foo.bar" is basically how BIND configuration files work, but there's no reason Twisted Names needs to work the same way. Since the pyzone files are already Python source, we can represent the wildcard using a bit more structure instead.

This should help clean up the implementation in the authority as well (though one is probably not necessary for the other). Gross string mashing with "*." + somestr should be avoided.

[Andrei]

What is the status for wildcard support? Bindzone wildcard seems also not supported though saying Adding IN Record *.example.com. 3600 <A address=1.2.3.4 ttl=3600>

[Richard Wall]

Here are some RFC reference to wildcard DNS records.

• serving wildcard records: ​https://tools.ietf.org/html/rfc1034#section-4.3.3
• caching wildcard records: ​https://tools.ietf.org/html/rfc1035#section-7.4

[Richard Wall]

Added RFC references to description.